feat: Add pr_url attribute to git providers and final update message in PR description

pr_agent/git_providers/codecommit_provider.py

@@ -61,6 +61,7 @@ class CodeCommitProvider(GitProvider):
         self.pr = None
         self.diff_files = None
         self.git_files = None
+        self.pr_url = pr_url
         if pr_url:
             self.set_pr(pr_url)
 

pr_agent/git_providers/gerrit_provider.py

@@ -192,7 +192,7 @@ class GerritProvider(GitProvider):
         )
         self.repo = Repo(self.repo_path)
         assert self.repo
-
+        self.pr_url = base_url
         self.pr = PullRequestMimic(self.get_pr_title(), self.get_diff_files())
 
     def get_pr_title(self):

pr_agent/git_providers/github_provider.py

@@ -31,6 +31,7 @@ class GithubProvider(GitProvider):
         self.diff_files = None
         self.git_files = None
         self.incremental = incremental
+        self.pr_url = pr_url
         if pr_url and 'pull' in pr_url:
             self.set_pr(pr_url)
             self.last_commit_id = list(self.pr.get_commits())[-1]

pr_agent/git_providers/gitlab_provider.py

@@ -37,6 +37,7 @@ class GitLabProvider(GitProvider):
         self.diff_files = None
         self.git_files = None
         self.temp_comments = []
+        self.pr_url = merge_request_url
         self._set_merge_request(merge_request_url)
         self.RE_HUNK_HEADER = re.compile(
             r"^@@ -(\d+)(?:,(\d+))? \+(\d+)(?:,(\d+))? @@[ ]?(.*)")