Replaced deprecated tslint with eslint, introduced prettier, editorconfig & stylelint

[astra1]

Description

As angular frontend project uses the obsolete tslint dependency, it has been replaced by eslint. Added prettier for code formatting. CSS styles are now validated using stylelint.

Fixes # (issue)

Type of change

Please delete options that are not relevant.

• 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 not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also
list any relevant details for your test configuration

• cd webapp && npm run lint
• cd webapp && npm run lint:styles

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• The commit message/PR follows our guidelines

Other information:

[plyubich]

Looks good

[plyubich]

Looks good. We should follow the new eslint style and reformat the code using prettier settings in the future

[ranadheer-b]

Looks good to me