Support the copied permalink for Github Enterprise URL

[hoontae24]

This PR is with respect to issue #3324

About Copying a Permalink:

• The problem is copyGithubPermalink is always copying as a permalink based on github.com
• If the remote upstream's fetch url is not based on "github.com", the copied permalink should be started upstream's url origin.
• It helps using Github Enterprise Server.

Applied Conditions

• You have to fill the Github Enterprise URI on VSCode config.(The attribute's name is github-enterprise.uri)

  • 

• The Host of your git remote repository's upstream equals to the host of Github Enterprise URI

• If the remote url is based on SSH, it checks equality of host(git@myenterprise.com => myenterprise.com) to the host of Github Enterprise URI

Let me know if there are any problems.

[ghost]

All CLA requirements met.

[alexr00]

Looks great, thank you for the PR!