Identical workouts in plan support

[pygoubet]

This PR fixes workout deletion step in case of multiple workouts with the same name exist.

./bin/console garmin:workout tests/Resource/3-weeks-plan.csv import -n -x

"40'@z2-3" and "9x1'@5k r1'30" are created 2 times, OK no big deal but a new delete/import will fail

./bin/console garmin:workout tests/Resource/3-weeks-plan.csv import -n -x
...
[error] Error thrown while running command "garmin:workout 'tests/Resource/3-weeks-plan.csv' import -n -x". Message: "An unexpected response code was found: 404"

In GarminConnect.php line 320:

  An unexpected response code was found: 404

It crashes because it tries to delete the "40'@z2-3" workout 2 times.

• Fix: src/Library/Handler/AbstractHandler.php L162 while + L166 unset -> all workouts with name $workoutName will be deleted

• Improvment: src/Library/Handler/AbstractHandler.php L100-129

# delete previous import
./bin/console garmin:workout tests/Resource/3-weeks-plan.csv import -n --delete-only
./bin/console garmin:workout tests/Resource/3-weeks-plan.csv schedule --start 2020-12-14 --no-interaction --delete

see in output "Workout - 40'@z2-3 was previously created on the Garmin website with the id" It will re-use existing workouts.

[Raistlfiren]

Thank you so much again!