feat: Add Git auth for GitHub, GitLab, Azure DevOps, and BitBucket (#4670)

* Add scaffolding

* Move migration

* Add endpoints for gitauth

* Add configuration files and tests!

* Update typesgen

* Convert configuration format for git auth

* Fix unclosed database conn

* Add overriding VS Code configuration

* Fix Git screen

* Write VS Code special configuration if providers exist

* Enable automatic cloning from VS Code

* Add tests for gitaskpass

* Fix feature visibiliy

* Add banner for too many configurations

* Fix update loop for oauth token

* Jon comments

* Add deployment config page

cli/config/server.yaml

@@ -0,0 +1,25 @@
+# Coder Server Configuration
+
+# Automatically authenticate HTTP(s) Git requests.
+gitauth:
+# Supported: azure-devops, bitbucket, github, gitlab
+# - type: github
+#   client_id: xxxxxx
+#   client_secret: xxxxxx
+
+# Multiple providers are an Enterprise feature.
+# Contact sales@coder.com for a license.
+# 
+# If multiple providers are used, a unique "id"
+# must be provided for each one.
+# - id: example
+#   type: azure-devops
+#   client_id: xxxxxxx
+#   client_secret: xxxxxxx
+# A custom regex can be used to match a specific
+# repository or organization to limit auth scope.
+#   regex: github.com/coder
+# Custom authentication and token URLs should be
+# used for self-managed Git provider deployments.
+#   auth_url: https://example.com/oauth/authorize
+#   token_url: https://example.com/oauth/token