Add browser() and other debugging calls as default undesirable functions

[MichaelChirico]

Leaving calls like browser() in the code after the bug is fixed is a common mistake; most "finished" code (especially in packages) shouldn't need to call this.

I believe the same goes for debug(), undebug(), trace(), untrace(), and debugcall().

I think it would make sense for these to be in the default set of undesirable functions for undesirable_function_linter.

Any second thoughts?

[AshesITR]

I agree, add debugonce() to the list.