Enable the "unparam" linter, which checks for unused function
parameters, unused function return values, and parameters and
return values that always have the same value every time they
are used.
In addition, fix many instances where the unparam linter complains
about our existing codebase. Remove error return values from a
number of functions that never return an error, remove or use
context and test parameters that were previously unused, and
simplify a number of (mostly test-only) functions that always take the
same value for their parameter. Most notably, remove the ability to
customize the RSA Public Exponent from the ceremony tooling,
since it should always be 65537 anyway.
Fixes#6104
0340b574d9