Feat: Add Theming with config.yml

[DeepanshKhurana]

Have you read the Contributing Guidelines?

Closes #14

Note to reviewers: This was changed before brand.yml came into the picture and works quite similarly. Still, since this is underway and has existing PRs in sequence (#17, #20), it would make sense to go forward with this and then, do a cleanup refactor to use brand.yml with minor changes, if necessary. Although, I don't see the need as of yet because the branding is not as widely present in this app, owing to its simplicity. But it can be something we decide in the future.

Description

• Adds config.yml branding + Sass modifications to access it
• Adds notes to README.md for the same
• Adds minor fix to onClick in the app list and job list reactable tables

Loom recording with demo

Definition of Done

• The change is thoroughly documented.
• The CI passes (R CMD check, linter, unit tests, spelling).
• Any generated files have been updated (e.g. .Rd files with roxygen2::roxygenise())

[jakubnowicki]

Hey, this is a nice improvement 👍 It needs a little bit more polishing; please check my comments.

[vituri]

Looks good! Later we will be able to use the new brand.yml file.

I see that all other comments by Jakub Nowicki were solved as well since his last review.

[DeepanshKhurana]

@jakubnowicki I believe we should be good here and @vituri already confirmed all the comments were addressed. I believe (2?) sequential branches have already been merged into this by him as well. So, we should avoid bloating this further and merge it. Additionally, I could not push to the main repository anymore (I assumed I would be able to do it but some permission issue prevented it) so I forked and created a !23 to add his suggestion for check_error_text() in his comment above. I suggest we merge that after we merge this to main.

[DeepanshKhurana]

@jakubnowicki Can we please merge this? I think this is pending a re-review from you still after @vituri's comments and review which confirms all the above items are addressed.