[5.1] Add Model::saveOrFail() to execute save operation within database transaction.

[crynobone]

This would simplify the following operation:

try {
    DB::transaction(function () use ($device) {
        $device->save();
    });
} catch (Exception $e) {
    return false;
}

to

try {
    $device->saveOrFail();
} catch (Exception $e) {
    return false;
}

Signed-off-by: crynobone [email protected]

[GrahamCampbell]

this function will not modify the saved variable - php puts it in a different scope

[GrahamCampbell]

Needs tests because the current implementation doesn't actually work.

[crynobone]

This tests follow testNestedTransactions() with the only different with using saveOrFail().

[crynobone]

Needs tests because the current implementation doesn't actually work.

Duplicate Illuminate\Database\Connection::transaction(), rebase and add tests.

[GrahamCampbell]

no need for all this, just use finally

[GrahamCampbell]

oh, wait, ignore me - we don't want to always rollback, lol