feat: add several contact types

[thesmiley1]

Summary

I wanted to add GitLab to footer contact icons and ended up adding a few others I thought could be useful.

Cleanups are in relevant files and structured as atomic commits.

What kind of change does this PR introduce? (check at least one)

• [ ] Bugfix
• [x] Feature
• [x] Code style update
• [ ] Refactor
• [x] Docs
• [ ] Build-related changes
• [ ] Other, please describe:

If changing the UI of default theme, please provide the before/after screenshot:

Does this PR introduce a breaking change? (check one)

• [ ] Yes
• [x] No

If yes, please describe the impact and migration path for existing applications:

The PR fulfills these requirements:

• [ ] When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number)

You have tested in the following browsers: (Providing a detailed version will be better.)

• [x] Chrome
• [x] Firefox
• [ ] Safari
• [ ] Edge
• [ ] IE

If adding a new feature, the PR's description includes:

• [x] A convincing reason for adding this feature
• [x] Related documents have been updated
• [ ] Related tests have been updated

To avoid wasting your time, it's best to open a feature request issue first and wait for approval before working on it.

Other information:

[billyyyyy3320]

Thanks. We definitely need linting and formatting.