feat(icons): adding provider icons

MR !4

• related website!8 (merged)

• Update to current logo https://about.gitlab.com/press/press-kit/ source is at https://gitlab.com/gitlab-com/www-gitlab-com/-/blob/103caec25d66e549ee9de6479d3009682f04db65/source/images/logos/gitlab-logo-color.svg

• check if setting the image path for emojis to be local .icon dir, that it'll pass a local website path instead of a cdn. see https://facelessuser.github.io/pymdown-extensions/extensions/emoji/#default-emoji-generators, if yes enable emoji

  • update docs for this feature