Push running checkpoint to remote (#6332)

* Push running checkpoint to remote

Fix #6182

* Update dvc/repo/experiments/executor/base.py

Co-authored-by: Peter Rowlands (변기호) <[email protected]>

* Get the branch name

* Finish this PR

1. move env name to dvc/env.py.
2. add some tests for it.

* Update after finally commit

* Some problems found in the review

1. change the behavior of self remote
2. do not use string DVC_EXP_AUTO_PUSH
3. downgrade the logger level in auto push
4. use full branch ref

* Update dvc/repo/experiments/executor/base.py

Co-authored-by: Peter Rowlands (변기호) <[email protected]>

* add a remote check before auto push

* Split current one env into two

* Rename DVC_EXP_CHECKPOINT_PUSH to DVC_EXP_AUTO_PUSH

* value error

* Remove getenv_bool switch to env2bool

* Better on handling Dulwich exceptions

* Name changing removing prints

* Update dvc/env.py

Co-authored-by: Peter Rowlands (변기호) <[email protected]>

* Some changes in review

* Add validation to repo URL

* Add new type of SCMError

* Update dvc/repo/experiments/executor/base.py

Co-authored-by: Peter Rowlands (변기호) <[email protected]>

* Use spy tests call counts and args

* Update dvc/scm/git/backend/base.py

Co-authored-by: Peter Rowlands (변기호) <[email protected]>

* Update dvc/scm/git/backend/dulwich.py

Co-authored-by: Peter Rowlands (변기호) <[email protected]>

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Remove validate_git_repo to validate_git_remote

Co-authored-by: Peter Rowlands (변기호) <[email protected]>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

dvc/scm/git/backend/gitpython.py

@@ -618,3 +618,6 @@ class GitPythonBackend(BaseGitBackend):  # pylint:disable=abstract-method
                 raise MergeConflictError("Merge contained conflicts") from exc
             raise SCMError("Merge failed") from exc
         return None
+
+    def validate_git_remote(self, url: str):
+        raise NotImplementedError