chore: optionally prefix authentication related cookies (#22148)

When the deployment option is enabled auth cookies are prefixed with
`__HOST-`
([info](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Set-Cookie)).

This is all done in a middleware that intercepts all requests and strips
the prefix on incoming request cookies.

coderd/apidoc/docs.go

@@ -15571,6 +15571,9 @@ const docTemplate = `{
         "codersdk.HTTPCookieConfig": {
             "type": "object",
             "properties": {
+                "host_prefix": {
+                    "type": "boolean"
+                },
                 "same_site": {
                     "type": "string"
                 },

coderd/apidoc/swagger.json

@@ -14092,6 +14092,9 @@
 		"codersdk.HTTPCookieConfig": {
 			"type": "object",
 			"properties": {
+				"host_prefix": {
+					"type": "boolean"
+				},
 				"same_site": {
 					"type": "string"
 				},