CSV Lookup builtin plugin

[narekhovhannisyan]

Types of changes

• Enhancement (project structure, spelling, grammar, formatting)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

A description of the changes proposed in the Pull Request

• This pull request adds CSV Lookup plugin to if framework's builtins.
• Covers the introduced changes with documentation and unit tests.
• Adds appropriate manifests samples.

[jmcook1186]

Added some test manifests and tidied up the readme, but otherwise this seems good. I have played around with it quite a bit and checked that it does what we expected. I haven't found any unexpected behaviour. Happy to pass to qa.

[MariamKhalatova]

@narekhovhannisyan When the value of output doesn't match with existing key, in the result output section a new param with the value of output value appears .
Expected result: Throw appropriate error

[MariamKhalatova]

@narekhovhannisyan When a value of output field is a two dimensional array and arrays contain only one field name, the output is broken.

[MariamKhalatova]

@narekhovhannisyan When plugin output is "*", outputs contain duplicates from query.

[MariamKhalatova]

@narekhovhannisyan please also check, all exported values are string.

[narekhovhannisyan]

@MariamKhalatova I've pushed fixes, please check