Checking for an exact match for product or serial and string descriptors can
lead to test failures if the USB devices connected to the runner is changed. This
commit adds some kconfig options to make the string descriptor checks optional,
with the product and serial string checks being disabled by default.
Previously, descriptors of the test devices were stored direclty in the mock
device files (e.g., "mock_[hid|msc].[h|c]"). This commit splits out the device
descriptors to separate files (e.g., "dev_[hid|msc].c") along with getter
functions.
Users that want to run the tests locally on a different device simply need to
update the "dev_[hid|msc].c" file for their device.
