Add link to search for code references to context of source strings via Crowdin API

After the original discussion, we decided to go further with adding the code references directly to the gitlab.pot file. But after the MR was opened gitlab-org/gitlab!166898 (closed), we discovered issues with this approach.

We have then settled on adding links to search for the code references directly to the source strings in Crowdin via the Crowdin API. Thic can be done by listing all strings, seeing which ones don't have this information yet in the context and then using string batch operation to update them all at once.

The goal of this task is to add these links to all strings in the prod Crowdin project and create a simple brief for our community and linguists. After this issue is finished, you can use the code for issue #276 (closed).