* Validate External Tracker URL Format

Add some validation checks for external tracker URL format.

Fixes #7068

* Don't make {index} a hard requirement

* Fix Description

* make fmt

* move regex to package level

* fix copyright date

* Clean up ref name rules

Clean up checks on reference names to better conform to the guideline
here: https://git-scm.com/docs/git-check-ref-format

This fixes half of #6321

* Update branch create integration test

According to: https://git-scm.com/docs/git-check-ref-format

And: git check-ref-format "master/feature=test1"

This is a valid branch name and we should not be testing for it to fail.

* Improve URL validation for external wiki  and external issues

* Do not allow also localhost address for external URLs

* Create new branch from branch selection dropdown and rewrite it to VueJS

* Make updateLocalCopyToCommit as not exported

* Move branch name validation to model

* Fix possible race condition

* Add correct git branch name validation

* Change git refname validation error constant name

* Implement URL validation based on GoLang url.Parse method

* Backward compatibility with older Go compiler

* Add git reference name validation unit tests

* Remove unused variable in unit test

* Implement URL validation based on GoLang url.Parse method

* Backward compatibility with older Go compiler

* Add url validation unit tests