Package Kit: reduce identifer/base-url confusion

For historical reasons, the package kit has an "url" field that is not
actually meant to be used as an URL. Rename it in the API and user
facing output as "identifier" to make it clear what the file is used
for. This change preserves the "url" key in on-disk and online storage
(hpkr files, stored settings, etc) in an attempt to not break anything.

Fix one remaining misuse of the "url" field as an URL in
get_package_dependencies.

Add an unit test showing that BUrl does parse "tab" URIs properly (there
is just a protocol and a path segment).

Change-Id: I339ce526e5798d42d78ae650855d7e988dbb4a1a
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2542
Reviewed-by: waddlesplash <waddlesplash@gmail.com>

HaikuDepot / PackageKit: Repositories 'Identifier' URL

Repositories are identified with a 'url' in the
remote 'repo.info' file. There is also a
'base url' which is the URL locally with which
the system is able to access the repository
data on. There is some confusion between these
two terms in the source. This change aims to
separate the two out and consistently name them.
The settings for the repository locally also was
not storing these values and that has been fixed.
Debug info about the repositories also did not
display the two urls consistently and will now
also do so. Finally, HaikuDepot now correlates
locally configured repositories with the data in
HaikuDepotServer using the identifier URL; this
makes the use of mirrors with HaikuDepot possible.

Fixes #13888
Change-Id: I66dfe589b05c24e1ab123a6945352e0f24b60bf1

Revert "repo rework: Re-add compatibility url field"
Revert "repo rework: Remove stubs; Breaks repo compat."
Revert "repo rework: Remove need for repos to be self-aware"

This reverts commit a2b2f4d6427914cdcdb59943dd8e4a0bfdcd53ee.
This reverts commit 602076ef82647a48fd10f4d1ec830bb4242f9eb6.
This reverts commit 5ffaf72c8a74a7eb6827e4d2b1f47c9360ddaefe.

These changes break the build on Haiku and the ability to create repo
mirrors, for the lack of a replacement for the URL (an UUID was evoked
on the mailing lists, but not implemented).

We are due for a release soon, please don't break the build.

repo rework: Remove need for repos to be self-aware

* See #12917 for details.
* Squashed to one commit to make revert easy if we
run into any issues.
* pkgman is now pre-attached to the 'current' repo
version within nightly images so they can be updated
by default.
* This shouldn't impact us keeping older sets of package
versions by commit hash for building older hrevs.
* There are XXX stubs with "Kill me". These will need
to be dropped after users are given sufficent time to
upgrade. We're dropping a previously required field (url)
so making this a slowish roll out.
* Makes the repos a lot less restrictive which should
help PM package building automation be a bit easier.
* Once this stuff smooths out, we'll add UUID's to the
repo definitions for duplicate repo detection.

create_repository_config: Make URL argument optional

If not specified, the URL from the repository info is used.

Add build tool create_repository_config

Given a repository base URL and a repository info, it creates a
repository config file.

create_repository_config: Make URL argument optional

If not specified, the URL from the repository info is used.

Add build tool create_repository_config

Given a repository base URL and a repository info, it creates a
repository config file.