Use LocalProbjectBuilder instead of old LocalProject constructor

[FrNecas]

Follow-up to https://github.com/packit/packit/pull/1558

The old usages should be removed, tests updated. Inspiration can be taken from adjustments in Packit CLI in the linked PR

Also consider if there are not unnecessary arguments/attributes in the API in the new class, e.g. we were debating whether remote and pr_id and similar still make sense.

EDIT [Jirka]: FYI, hardly code should be updated in packit/hardly#92