The using the "first available" numbering option, force an
artifical linear numbering scheme starting at '1'.
Start the pad name provider at the 0'th pad index.
Also adds a few related tests and adjusts tests affected by
this change to reflect that the offset still applies.
This can be expanded in future to be more general by skipping
pad (which would allow a custom start and numbering scheme
while still avoiding duplication), but for now,
this does what the UI says and avoids string changes in 5.1rc.
Fixes: lp:1814918
* https://bugs.launchpad.net/kicad/+bug/1814918
Fixes: lp:1814917
* https://bugs.launchpad.net/kicad/+bug/1814917
The geometry and numbering logic is separate to the dialog, and
can be separated for clearer logic and better testability.
Moreover, refactor it to avoid any dependency on pcbnew
classes, so it can be move to common for potential re-use in
eeschema and friends in future.
Also convert all wxPoint logic in these classes to VECTOR2I and
fix some function visibilities.
Add some unit tests of the ARRAY_OPTIONS geometry and numbering.
John Beard