Test commit with CLI commands moved onto Settings object

[DiamondJoseph]

Dummy commit to test out possible new pattern of how to create commands.
This form ensures that Settings object has been fully resolved before any commands are run, meaning that the Settings object can be treated as effectively immutable.

This pattern can be recursed down, with e.g.

class Settings(BaseSettings):
    command: CliSubCommand[Union[Client, Server]]

    def cli_cmd(self):
        CliApp.run_subcommand(self)

class Client(BaseModel):
    subcommand: CliSubCommand[Union[InMemory, FromUri]]

    def cli_cmd(self):
        CliApp.run_subcommand(self)

class InMemory(BaseModel):

    def cli_cmd(self):
        ...

Checklist

• Add a Changelog entry
• Add the ticket number which this PR closes to the comment section

[DiamondJoseph]

Deprecated and replaced by #930, a much more complete example.