[Drill Output][Added] Option to omit generation of drill files

[nguyen-v]

This PR adds the generate_drill_files option (default True) to the gerb_drill and excellon outputs. This is useful when one wants to only generate the drill map without drill files.

[set-soft]

Ok, thanks!

[set-soft]

Just a couple of comments:

1. You don't need to add it to excellon and gerb_drill, both are "any_drill"
2. You don't need to modify the RST files, they are generated from the source code using "make doc"

[nguyen-v]

Just a couple of comments:

1. You don't need to add it to excellon and gerb_drill, both are "any_drill"
2. You don't need to modify the RST files, they are generated from the source code using "make doc"

Good to know, will take note for any future PR