Fix: Restore GitLabDSL.api to be GitLabAPI instance

[glensc]

Revert "Ensures that the Gitlab API is exposed properly through the dts"

This reverts commit e8d2052.

The breakage introduced between 10.6.5 and 10.6.6 patch version update

Refs:

• [BUG] addLabels not a function #1314 (comment)

[glensc]

I think there aren't many gitlab users that has gone un-noticed that long. at least the write methods.

I do use gitlab, not so far did not need to use write functions, just used danger.gitlab json structures

[glensc]

@orta who can give insights and directions on how to the problem? only you?

[orta]

Yep, I do OSS in my increasingly little spare time and so mainly only have time for well formed non-draft PRs

[glensc]

hmm. I can no longer update this branch

ERROR: Permission to danger/danger-js.git denied to glensc.
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

[glensc]

Closing:

1. Developer permissions revoked (can't update pr).
2. No longer need this.