libmodprobe: Define ModuleConfig

This commit defines ModuleConfig, which parses module configurations and
stores the needed information to its members.  The parsing logic remains
the same as in the original implementation in the Modprobe constructor.
Now the Modprobe constructor will build and use an instance of
ModuleConfig.

Bug: 421025789
Test: DUT boots
Test: atest libmodprobe/module_config_test.cpp
Change-Id: I5df01e72db86708a572bcd4eba7fdc142cfe6f53