chore: rename git_auth to external_auth in our schema (#9935)

* chore: rename `git_auth` to `external_auth` in our schema

We're changing Git auth to be external auth. It will support
any OAuth2 or OIDC provider.

To split up the larger change I want to contribute the schema
changes first, and I'll add the feature itself in another PR.

* Fix names

* Fix outdated view

* Rename some additional places

* Fix sort order

* Fix template versions auth route

* Fix types

* Fix dbauthz

coderd/database/queries/templateversions.sql

@@ -105,11 +105,11 @@ SET
 WHERE
 	job_id = $1;
 
--- name: UpdateTemplateVersionGitAuthProvidersByJobID :exec
+-- name: UpdateTemplateVersionExternalAuthProvidersByJobID :exec
 UPDATE
 	template_versions
 SET
-	git_auth_providers = $2,
+	external_auth_providers = $2,
 	updated_at = $3
 WHERE
 	job_id = $1;