Improve Configuration UI

[yne]

This PR:

• Group configuration by categories
• Allow simple array and object modification from UI using the VScode "Add Item" action

How:

• By declaring an array of categories (each category contain the same "properties" values as before)
• By adding an additionalProperties attribute on object/list configurations params
• By updating the relevant intellij/package python generator

Preview:

Verification

Because of the new indentation level, this PR has a lot of changed lines,
In order to check that all attributes are still here from the previous package.json we can

diff \
<(jq '.contributes.configuration[].properties | keys[]' < package.json | sort)\
<(jq '.contributes.configuration.properties|keys[]' < package_ori.json | sort)

[CLAassistant]

All committers have signed the CLA.

[fabioz]

Sorry for the really late reply (I just saw this PR now).

Actually the package.json is generated from running robotframework-lsp/codegen/codegen_package.py, so, it cannot be changed directly (you need to update the code that generates it...).

[yne]

@fabioz
good to know, I'll take a look

[yne]

@fabioz : I've updated the relevant generator in 617dd1d then run a pass of generation that I've put in a 3rd commit 7f9fadc

Tell me if I forgot any other files :)