This integrates various pieces of ground work:
 - [Migrating a POST request to a GraphQL mutation][gql]
 - [Creating an expandable container component][exp]
 - [Creating an AnalyzerConfiguration component][ac1]
 - [Extending the AnalyzerConfiguration component][ac2]

This is implemented behind the `sast_configuration_ui_analyzers` feature
flag, since the necessary backend changes are not yet in place. A future
iteration will enable or remove the feature flag.

Other changes include:
 - Explicitly pass the disabled prop to child fields, so they can hide
   the custom value message when disabled
 - Relax the analyzer entity prop validator, since the description is
   nullable, and the template already handles this

Addresses https://gitlab.com/gitlab-org/gitlab/-/issues/238602, part of
https://gitlab.com/groups/gitlab-org/-/epics/3635.

[gql]: https://gitlab.com/gitlab-org/gitlab/-/issues/227575
[exp]: https://gitlab.com/gitlab-org/gitlab/-/issues/233521
[ac1]: https://gitlab.com/gitlab-org/gitlab/-/issues/238600
[ac2]: https://gitlab.com/gitlab-org/gitlab/-/issues/238603