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* Fix outdated view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

cli/create_test.go

@@ -609,11 +609,11 @@ func TestCreateWithGitAuth(t *testing.T) {
 	}
 
 	client := coderdtest.New(t, &coderdtest.Options{
-		GitAuthConfigs: []*gitauth.Config{{
+		ExternalAuthConfigs: []*gitauth.Config{{
 			OAuth2Config: &testutil.OAuth2Config{},
 			ID:           "github",
 			Regex:        regexp.MustCompile(`github\.com`),
-			Type:         codersdk.GitProviderGitHub,
+			Type:         codersdk.ExternalAuthProviderGitHub,
 		}},
 		IncludeProvisionerDaemon: true,
 	})