Add deb repository and remote pages

[warisshaikh1]

Addresses part of #277 (deb in the side menu).

Draft on purpose — I asked three scoping questions in #277 and haven't heard back yet. This is here so there's something concrete to react to rather than to pre-empt the answers. Happy to cut it down, extend it, or restructure it entirely.

What this adds

A Pulp deb menu section gated on hasPlugin('deb'), with Repositories and Remotes, mirroring Pulp file:

	list	detail	edit	tabs
remotes/deb/apt	yes	yes	yes	details
repositories/deb/apt	yes	yes	yes	details, versions, distributions

What it deliberately leaves out

• Publications. deb has two publication endpoints rather than a field: publications/deb/apt generates fresh metadata and needs a signing service to be consumable, while publications/deb/verbatim republishes upstream's Release/InRelease byte for byte so an ordinary ubuntu-archive-keyring verifies it. A publications tab has to either show both or ask which to create, which is a design decision rather than wiring, so it seemed better to agree it first.
• Content browsing. content/deb/packages is the useful one, but there are a dozen deb content endpoints where rpm has one. Easy follow-up once the shape here is agreed.

The one place deb genuinely differs from file

RemoteForm needed the APT fields, which have no equivalent elsewhere: distributions (suites), components, architectures, gpgkey, and the sync_sources / sync_udebs / sync_installer switches.

distributions is required, for deb only. Every other plugin's remote needs just a URL; pulp_deb rejects one without suites:

POST /pulp/api/v3/remotes/deb/apt/
{"name":"x","url":"http://deb.debian.org/debian/","tls_validation":true,"download_concurrency":10}
-> 400 {"distributions": ["This field is required."]}

So requiredFields becomes conditional. gpgkey reuses the FileUpload treatment ca_cert and client_cert already get, since it's an armoured key file rather than a one-line value.

Everything else is registry entries — plugin2api, the plugin unions on LazyRepositories / LazyDistributions / RepositoryForm, and deb-only optional fields on the shared RemoteType. All additive; ansible, container and file behaviour is unchanged (the RemoteForm diff is worth a look on that point specifically).

Testing

Verified against a live pulpcore 3.116.0 / pulp_deb 3.10.0 mirroring Ubuntu noble, with the dev server proxied at it (API_PROXY):

• every query the new pages issue returns 200 — remote and repository lists with ordering / name__icontains / pulp_label_select / remote filters, …/versions/, …/versions/?number=N, and distributions/deb/apt/?repository=<href>
• the exact create payload DebRemoteEdit sends → 201; the smartUpdate PUT with all APT fields → 202, and the fields read back verbatim
• the repository create plus auto-created distribution path → 201 / 202, and pluginRepositoryBasePath('deb', …) resolves the base_path the Repository URL field shows
• test objects cleaned up afterwards, existing content untouched

npm run lint:js, lint:ts, lint:ls, the this-without-class check and npm run build are all clean (build warnings unchanged at 18, all pre-existing bundle-size ones). No CHANGES.md entry, since that's generated from PR titles at release.

Two things I'd flag for review

1. A third copy of SyncModal. ansible-repository-sync.tsx and file-repository-sync.tsx already carry identical copies and I've followed suit rather than refactoring inside a feature PR. Happy to extract all three into a shared component, here or separately, if you'd prefer.
2. mirror defaults to true in the sync modal, matching the other plugins, though pulp_deb's own API default is false. I kept UI consistency, but say the word and I'll flip it — mirroring is the destructive direction.

@bmbouter @himdel @dkliban @ipanova