Allow construction to find materials while standing on stairs

[RoyBerube]

Summary

Bugfixes "Allow construction to find materials while standing on stairs"

Purpose of change

Fixes #51187

While standing on stairs and doing a construction, the player would only see ingredients and tools in inventory.

Describe the solution

This adds a condition to not ignore the location where the player is standing when searching for ingredients/tools. If the player was on stairs it would reject that location and then all other locations would be unreachable as a result.

Describe alternatives you've considered

Changing the signature for has_floor_or_support(). This is less disruptive.

Testing

Using the construction menu while standing on stairs.

Additional context

[dseguin]

I tried this out standing on stairs with materials nearby:

Without the fix, the materials are not used:

Using this PR, it seems to be fixed: