brands: migrate custom CSS to brands (#13172)

* brands: migrate custom CSS to brands

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* fix missing default

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* fix tests

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* simpler migration

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* add css to brand form

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* fix

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

---------

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

web/scripts/build-web.mjs

@@ -52,7 +52,6 @@ const definitions = Object.fromEntries(
 const assetsFileMappings = [
     ["node_modules/@patternfly/patternfly/patternfly.min.css", "."],
     ["node_modules/@patternfly/patternfly/assets/**", ".", "node_modules/@patternfly/patternfly/"],
-    ["src/custom.css", "."],
     ["src/common/styles/**", "."],
     ["src/assets/images/**", "./assets/images"],
     ["./icons/*", "./assets/icons"],