cli/command: deprecate Cli.ManifestStore, Cli.RegistryClient

[thaJeztah]

• relates to cli/command, cil/command/image: remove deprecated methods and functions #5876

---

cli/command: internalize constructing ManifestStore

The CLI.ManifestStore method is a shallow wrapper around manifeststore.NewStore
and has no dependency on the CLI itself. However, due to its signature resulted
in various dependencies becoming a dependency of the "command" package.
Consequence of this was that cli-plugins, which need the cli/command package,
would also get those dependencies.

• This patch inlines the code to produce the store, skipping the wrapper.
• Define a local interface for some tests where a dummy store was used.

cli/command: internalize constructing RegistryClient

The CLI.RegistryClient method is a shallow wrapper around registryclient.NewRegistryClient
but due to its signature resulted in various dependencies becoming a dependency
of the "command" package. Consequence of this was that cli-plugins, which
need the cli/command package, would also get those dependencies.

This patch inlines the code where needed, skipping the wrapper

cli/command: deprecate Cli.ManifestStore

This method is a shallow wrapper around manifeststore.NewStore, but
due to its signature resulted in various dependencies becoming a dependency
of the "command" package. Consequence of this was that cli-plugins, which
need the cli/command package, would also get those dependencies. It is no
longer used in our code, which constructs the client in packages that need it,
so we can deprecate this method.

cli/command: deprecate Cli.RegistryClient

This method was a shallow wrapper around registryclient.NewRegistryClient but
due to its signature resulted in various dependencies becoming a dependency
of the "command" package. Consequence of this was that cli-plugins, which
need the cli/command package, would also get those dependencies. It is no
longer used in our code, which constructs the client in packages that need it,
so we can deprecate this method.

- Human readable description for the release notes

Go SDK: `cli/command`: deprecate `Cli.RegistryClient`. This method was only used internally and will be removed in the next release. Use [`client.NewRegistryClient`](https://pkg.go.dev/github.com/docker/cli@v28.0.1+incompatible/cli/registry/client#NewRegistryClient) instead.
Go SDK: `cli/command`: deprecate `Cli.RegistryClient`. This method was only used internally and will be removed in the next release. Use [`client.NewRegistryClient`](https://pkg.go.dev/github.com/docker/cli@v28.0.1+incompatible/cli/registry/client#NewRegistryClient) instead

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[codecov-commenter]

Codecov Report

Attention: Patch coverage is 61.11111% with 14 lines in your changes missing coverage. Please review.

Project coverage is 59.29%. Comparing base (c775585) to head (8ad0721).
Report is 10 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5889      +/-   ##
==========================================
+ Coverage   58.90%   59.29%   +0.38%     
==========================================
  Files         351      354       +3     
  Lines       29727    29752      +25     
==========================================
+ Hits        17511    17640     +129     
+ Misses      11242    11140     -102     
+ Partials      974      972       -2