Unable to use CommaDelimitedList Parameters as inputs to intrinsic functions

[jamesmcminn96]

Hi! Thanks for the great tool.

Versions
Python: 3.11
cloud-radar: https://github.com/DontShaveTheYak/cloud-radar/tree/0.12.0

Issue
With the following simplified template I'm unable to make use of CommaDelimitedList effectively when passing parameters of that type into other functions.

Parameters:
  AllowedWriters:
    Type: CommaDelimitedList
    Description: Principals allowed to write

Conditions:
  EmptyList:
    !Equals
      - !Join ["", !Ref AllowedWriters]
      - ""

The following code:

from cloud_radar.cf.unit import Template

cloudformation_template = Template.from_yaml('template.yaml')

stack_cdl = cloudformation_template.create_stack({
    'AllowedWriters': 'abc,123'
})

stack_list = cloudformation_template.create_stack({
    'AllowedWriters': ['abc','123']
})

`stack_cdl` results in the error:

Traceback (most recent call last):
  File "/Users/james/code/scratch/cloud-radar-patch/main.py", line 4, in <module>
    stack = cloudformation_template.create_stack({
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/james/.local/share/virtualenvs/cloud-radar-patch-LSQMlmdS/lib/python3.11/site-packages/cloud_radar/cf/unit/_template.py", line 322, in create_stack
    self.render(params, parameters_file=parameters_file)
  File "/Users/james/.local/share/virtualenvs/cloud-radar-patch-LSQMlmdS/lib/python3.11/site-packages/cloud_radar/cf/unit/_template.py", line 158, in render
    self.template = self.render_all_sections(self.template)
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/james/.local/share/virtualenvs/cloud-radar-patch-LSQMlmdS/lib/python3.11/site-packages/cloud_radar/cf/unit/_template.py", line 254, in render_all_sections
    template["Conditions"] = self.resolve_values(
                             ^^^^^^^^^^^^^^^^^^^^
  File "/Users/james/.local/share/virtualenvs/cloud-radar-patch-LSQMlmdS/lib/python3.11/site-packages/cloud_radar/cf/unit/_template.py", line 354, in resolve_values
    data[key] = self.resolve_values(
                ^^^^^^^^^^^^^^^^^^^^
  File "/Users/james/.local/share/virtualenvs/cloud-radar-patch-LSQMlmdS/lib/python3.11/site-packages/cloud_radar/cf/unit/_template.py", line 384, in resolve_values
    value = self.resolve_values(
            ^^^^^^^^^^^^^^^^^^^^
  File "/Users/james/.local/share/virtualenvs/cloud-radar-patch-LSQMlmdS/lib/python3.11/site-packages/cloud_radar/cf/unit/_template.py", line 400, in resolve_values
    return [
           ^
  File "/Users/james/.local/share/virtualenvs/cloud-radar-patch-LSQMlmdS/lib/python3.11/site-packages/cloud_radar/cf/unit/_template.py", line 401, in <listcomp>
    self.resolve_values(
  File "/Users/james/.local/share/virtualenvs/cloud-radar-patch-LSQMlmdS/lib/python3.11/site-packages/cloud_radar/cf/unit/_template.py", line 384, in resolve_values
    value = self.resolve_values(
            ^^^^^^^^^^^^^^^^^^^^
  File "/Users/james/.local/share/virtualenvs/cloud-radar-patch-LSQMlmdS/lib/python3.11/site-packages/cloud_radar/cf/unit/_template.py", line 400, in resolve_values
    return [
           ^
  File "/Users/james/.local/share/virtualenvs/cloud-radar-patch-LSQMlmdS/lib/python3.11/site-packages/cloud_radar/cf/unit/_template.py", line 401, in <listcomp>
    self.resolve_values(
  File "/Users/james/.local/share/virtualenvs/cloud-radar-patch-LSQMlmdS/lib/python3.11/site-packages/cloud_radar/cf/unit/_template.py", line 389, in resolve_values
    funct_result = allowed_func[key](self, value)
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/james/.local/share/virtualenvs/cloud-radar-patch-LSQMlmdS/lib/python3.11/site-packages/cloud_radar/cf/unit/functions.py", line 555, in join
    raise TypeError(
TypeError: Fn::Join-- The first value must be a String and the second a List.

`stack_list` results in the error:

Traceback (most recent call last):
  File "/Users/james/code/scratch/cloud-radar-patch/main.py", line 4, in <module>
    stack = cloudformation_template.create_stack({
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/james/.local/share/virtualenvs/cloud-radar-patch-LSQMlmdS/lib/python3.11/site-packages/cloud_radar/cf/unit/_template.py", line 322, in create_stack
    self.render(params, parameters_file=parameters_file)
  File "/Users/james/.local/share/virtualenvs/cloud-radar-patch-LSQMlmdS/lib/python3.11/site-packages/cloud_radar/cf/unit/_template.py", line 154, in render
    self.set_parameters(params)
  File "/Users/james/.local/share/virtualenvs/cloud-radar-patch-LSQMlmdS/lib/python3.11/site-packages/cloud_radar/cf/unit/_template.py", line 520, in set_parameters
    validate_parameter_constraints(
  File "/Users/james/.local/share/virtualenvs/cloud-radar-patch-LSQMlmdS/lib/python3.11/site-packages/cloud_radar/cf/unit/_template.py", line 557, in validate_parameter_constraints
    for part in parameter_value.split(","):
                ^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'list' object has no attribute 'split'

It appears that functions like Join and Select within the template are unable to handle the case where the parameter is a CommaDelimitedList. It expects it to be both a list and a string it can split on.