feat: allow configuring OIDC email claim and OIDC auth url parameters (#6867)

This commit:

- Allows configuring the OIDC claim Coder uses for email addresses (by default, this is still email)
- Allows customising the parameters sent to the upstream identity provider when requesting a token. This is still access_type=offline by default.
- Updates documentation related to the above.

coderd/apidoc/docs.go

@@ -7294,6 +7294,9 @@ const docTemplate = `{
                 "allow_signups": {
                     "type": "boolean"
                 },
+                "auth_url_params": {
+                    "type": "object"
+                },
                 "client_id": {
                     "type": "string"
                 },
@@ -7306,6 +7309,9 @@ const docTemplate = `{
                         "type": "string"
                     }
                 },
+                "email_field": {
+                    "type": "string"
+                },
                 "group_mapping": {
                     "type": "object"
                 },

coderd/apidoc/swagger.json

@@ -6532,6 +6532,9 @@
         "allow_signups": {
           "type": "boolean"
         },
+        "auth_url_params": {
+          "type": "object"
+        },
         "client_id": {
           "type": "string"
         },
@@ -6544,6 +6547,9 @@
             "type": "string"
           }
         },
+        "email_field": {
+          "type": "string"
+        },
         "group_mapping": {
           "type": "object"
         },