Fix overwrite not working for ctapipe-apply-models

[maxnoe]

Because there was no alias defined for the HDF5Merger component the --overwrite option had no effect for ctapipe-apply-models.

[Tobychev]

@maxnoe I edited the description with that I guessed the fix was, if you confirm the guess is accurate I can approve.

[maxnoe]

@Tobychev thanks, yes!

[kosack]

Because there was no alias defined for the HDF5Merger component the --overwrite option had no effect

Doesn't this mean that there simply wasn't an --overwrite option at all in the Tool? if so, passing --overwrite on the command-line should have raised an exception due to an unknown alias, right?

[maxnoe]

Doesn't this mean that there simply wasn't an --overwrite option at all in the Tool? if so, passing --overwrite on the command-line should have raised an exception due to an unknown alias, right?

The option now lives on the Tool itself, it only needs to be overridden if a tool as a sub-component that also needs the option.