This should eliminate all non-variable color usage in the styles, making
gitea fully themeable via CSS variables. Also, it adds a linter to
enforce variables for colors.

- Update all JS dependencies to latest version
- Disable two redundant eslint rules
- Adapt stylelint config to codebase
- Regenerate SVGs
- Make file editor spinner "reserve" height so page does not shift
- Tested katex, swagger, monaco

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: 6543 <6543@obermui.de>

- Updated all JS dependencies minus Vue (update 2 to 3 requires a ton of
  work and is probably blocked by dependencies)
- Tested editor, swagger-ui

- Update monaco, adapting to breaking changes
- Update dropzone, adapting to breaking changes
- Update linters, fix new issues, disable opinionated stylelint rules
- Rebuild SVGs and images
- Tested Dropzone and Monaco

Replaces: https://github.com/go-gitea/gitea/pull/17574

Add a new default theme `auto`, which will automatically switch between
`gitea` (light) and `arc-green` (dark) themes depending on the user's
operating system settings.

Closes: #8183

- Convert all tooltips to JS-based ones, fixing overflow issues
- Restyle issue dependencies/dependants
- Move popup styles to base style
- CSS Helper tweaks
- Unify pseudo element selectors and lint for it

Fixes: https://github.com/go-gitea/gitea/issues/13400

- replace two instances of fontawesome with octicons
- add new "class" optional argument to "svg" helper
- add many new CSS helpers and move their import to the end for
  increaseed precedence

Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

Reindent and unify codebase to 2-space indentation.

Rendering the git graph on the server means that we can properly track flows and switch from the Canvas implementation to a SVG implementation.

* This implementation provides a 16 limited color selection
* The uniqued color numbers are also provided
* And there is also a monochrome version
*In addition is a hover highlight that allows users to highlight commits on the same flow.

Closes #12209

Signed-off-by: Andrew Thornton art27@cantab.net
Co-authored-by: silverwind <me@silverwind.io>

Enabled the rule and --fix'ed issues.

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

- move "vendor" files to js/vendor and less/vendor
- move swagger to js/standalone (meant for standalone pages)
- move gitgraph to features and streamline its loading
- add linting configs to webpack dependencies in make
- set ignored files for eslint/stylelint directly in their configs

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: Antoine GIRARD <sapk@users.noreply.github.com>

New CSS linter which is much more powerfull than the previous one.
Configuration is default but I had to remove a few rules that were
throwing too many or weird errors.

More importantly, the linter will exit with code 1 on errors so now our
build will fail if the CSS linter fails which should eliminate linter
errors being introduced without notice.