Add the slic dump command to create dump.sql

[defunctl]

Adds the slic dump command based on my shell script which performs the same functionality, essentially creating a raw dump.sql for acceptance tests.

I'm not tied to any specific command names or descriptions, so let me know if you need changes.

Help Screen:

[lucatume]

The most likely use case is one of a plugin developer "getting" a new version of WordPress together with slic and having to update the file dumps.
For that reason I would make the WordPress version update optional, and the file required.

I think the command should be called dump-update or something along the line of suggesting that there is an update of the dump involved.

Furthermore, to stick with slic style of input, I would remove the -- options and decide upon the order of arguments.
E.g. slic dump-update <file> [<wp_version>]

slic dump-update tests/_data/dump.sql
slic dump-update tests/_data/dump.sql 6.4.3

Lastly, I understand and appreciate the --yes package-managerism, but the operation is easily reversible with a git checkout (dumps are under version control) and I would just run the update, without confirmation.