alpha/baker: replace force_apply with force_apply_from_round

What

Replace --force-apply baker argument with --force-apply-from-round

Why

The baker currently applies block from round 0 if --force_apply is used, and from round 1 otherwise.

We want the default to be set to 3, with the option to adjust it using --force-apply-from-round <round>.

How

In addition to the aforementioned changes :

• Added a field forced_applied to the baker event forging_block to allow block application monitoring from Tezt.
• Added a Tezt test.

Note that this work has been backported to 021_PsquebeC

Manually testing the MR

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR