signapk currently accepts a Provider class that can be instantiated
and inserted before the signing. This commit adds support to specify
a -providerArg parameter that can be used to configure the Provider.
Prior to JDK 9 a Provider would accept a providerArg in a constructor
accepting a String; in JDK 9+ a Provider should first be instantiated
with the zero-arg constructor, then the configure method should be
called with the providerArg.
Bug: 142334653
Bug: 190974913
Fixes: 232134730
Test: Manually verified new Provider can be inserted with pre- and
post-JDK 9 behavior.
Change-Id: I96f027640c59d3357e8dcf656626d1601bfef861
2f8aad4f7f