Upgrade Omniauth and JWT gems to switch away from Google+ API

CE port: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/24068

• omniauth-google-oauth2: Google will be deprecating its support for the Google+ API, which currently omniauth-google-oauth2 uses to retrieve user info.

  • https://github.com/zquestz/omniauth-google-oauth2/pull/344/files removes Google+ endpoints.
  • The bump in omniauth-google-oauth2 requires an upgrade to ruby-jwt v2+ to support the verification of multiple issue providers (https://github.com/zquestz/omniauth-google-oauth2/pull/345).

• jwt: This has the most number of changes that need to be reviewed: https://github.com/jwt/ruby-jwt/blob/master/CHANGELOG.md

• oauth2: Needed to support ruby-jwt v2+: https://github.com/oauth-xx/oauth2/blob/master/CHANGELOG.md

• omniauth-azure-oauth2: Needed to support ruby-jwt v2+: https://github.com/KonaTeam/omniauth-azure-oauth2/compare/v0.0.9...v0.0.10

• omniauth: This version bump only involves backstage improvements: https://github.com/omniauth/omniauth/releases, https://github.com/omniauth/omniauth/compare/v1.8.1...v1.9.0

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/55668