Resolve "WebIDE Default Commit options"

Closes #51470

See merge request gitlab-org/gitlab-ce!31449

One exception: there is an existing MR for the current branch and the
branch is non-default and non-protected.

Extended mock_data for ide/stores to have different types of branches:
default, protected and regular

Cleaned new MR checkbox view

Resolve "Mirroring for external CI/CD repositories should not store OAuth token"

See merge request gitlab-org/gitlab-ce!31488

Oauth2 tokens are causing issues with mirroring
repos, because it effectively limits the number
of repos you can mirror. Personal Access
Tokens do not have this problem.

This change removes the OAuth2 option from
the import page for CI/CD only, and only
provides the personal access token form.

Update QA readme to note that Chrome/Chromium is required

See merge request gitlab-org/gitlab-ce!32035

Fix "ERR value is not an integer or out of range" errors

Closes #66449

See merge request gitlab-org/gitlab-ce!32126

Expose namespace storage statistics with GraphQL

See merge request gitlab-org/gitlab-ce!32012

Root namespaces have storage statistics.
This commit allows namespace owners to get those stats via GraphQL
queries like the following one

{
  namespace(fullPath: "a_namespace_path") {
    rootStorageStatistics {
      storageSize
      repositorySize
      lfsObjectsSize
      buildArtifactsSize
      packagesSize
      wikiSize
    }
  }
}