Rename all the arguments expecting a dependency type to "deptypes" #29397
Description
See discussion in #28673 (comment)
In Spack's codebase we have functions that take a deptype= argument, and other functions that take a deptypes= argument. This is confusing and might lead to typo and ultimately bug in the code. We need to standardize on one spelling.
These bugs have already been fixed in develop, but for instance we had a call:
spack/lib/spack/spack/package.py
Line 1192 in 1ddad52
using deptypes= and expecting the other argument:
Line 1350 in 1ddad52