Searches by URL for self hosted GitHub and GitLab on Launchpad

[sergeibbb]

Description

• Adds search by URL for GitLab Self Managed to the Launchpad
• Adds search by URL for GitHub Enterprise to the Launchpad

Checklist

• I have followed the guidelines in the Contributing document
• My changes follow the coding style of this project
• My changes build without any errors or warnings
• My changes have been formatted and linted
• My changes include any required corresponding changes to the documentation (including CHANGELOG.md and README.md)
• My changes have been rebased and squashed to the minimal number (typically 1) of relevant commits
• My changes have a descriptive commit message with a short title, including a Fixes $XXX - or Closes #XXX - prefix to auto-close the issue that your PR addresses

[sergeibbb]

@axosoft-ramint

Now it doesn't harm users. Just search by URL doesn't work for self hosted GitHub and GitLab. That is why I suppose this PR can be merged after the release as a follow-up.

I haven't changed the CHANGELOG yet, because if we decide to merge before the release, it will be covered by general notes of adding self-hosted GitLab and GitHub.

Also, I've noticed that GitLab's and GitHub's methods are similar: they get a value without provider field and then extend it with this.id. I wanted to move it to the base class, but the return type is incompatible with Jira.