split functions

[hohwille]

In devonfw-ide we have created reusable functions in a file called functions.
We also have 2 special functions in environment-project for more global reuse.
This is because when you just call devon without arguments the script can not be executed as a sub-process as it needs to "tweak" variables like PATH of the current shell.
If we would source the functions here, we would pollute the callers shell with tons of functions (including side-effects and seeing them in tab-completion, etc.).
Therefore we only source environment-project.
To avoid redundancies environment-project defines these 2 functions that are also reused in commandlets and other functions.
Therefore they are declared in environment-project but when devon is called without arguments, it will afterwards "unload" these 2 functions to remove them from the callers shell.
The commandlets source functions that again sources environment-project.

Now, with PR #934 and issue #878 we have extended some cross-cutting functionality executed in functions.
Also we have to define some things in commandlets before we source functions.
If in this case we want to use some function like e.g. doIsWindows or doIsMacOs we can not do so as the function is not yet defined at that point.
As a result so far I have copied the logic from such functions into the commandlet.
It is about time to rethink this approach and come up with a clean design resolving this problem.
IMHO we should have two files that only declare functions and have (almost) no side effects:

• functions-core
  (if someone has a better name for this, please go ahead)
• functions
  (only side effects: source functions-core, handle DEVON_IDE_TRACE, set DEVON_IDE_HOME)

The side effects should happen in the following files:

• environment-project
  (sources functions-core and then does what it already does currently except declaring functions what is moved to functions-core)
• commandlet-cli
  (here we extract the current side-effects of functions what is at the bottom of the file and parsing CLI paramters)

As a result a commandlet header will look like this:

#!/usr/bin/env bash

# autocompletion list
if [ "${1}" = "shortlist" ]
then
  ...autocompletion here...
  exit
fi

# the following line will be moved to the end of functions and removed from all commandlets
#if [ -n "${DEVON_IDE_TRACE}" ]; then set -vx; fi
# shellcheck source=scripts/functions
source "$(dirname "${0}")"/../functions
«TOOL»_HOME="${DEVON_IDE_HOME}/software/«tool»"
... here we can already use any function
TOOL_VERSION_COMMAND=...
#override functions such as doResolveDownloadUrl here
# shellcheck source=scripts/commandlet-cli
source "$(dirname "${0}")"/../commandlet-cli
... rest of the commandlet with doSetup, cli-parsing, etc. ...