Create LicensingService stub

[Uldiniad]

No description provided.

[Uldiniad]

Should fix (at least some of) the following issues
microg/GmsCore#2050
#47
https://gitlab.com/CalyxOS/calyxos/-/issues/1510
microg/GmsCore#46

[chirayudesai]

Test: https://play.google.com/store/apps/details?id=com.sap.mdc.loblaw.nativ

Many of the other apps listed worked fine either way.

[vincentvidal]

A similar solution has been implemented in the FakeStore version distributed for iodéOS: through our f-droid repo since March 14 and in iodéOS v4.1 released on April 2 (we left the aidl files taken from here for some experiments, although not useful for the stub).
I can confirm that many apps work with this patch, with the exception of Tasker as reported by several users, which was working without the stub.

[mar-v-in]

A similar, yet more complete version of the License Service was added as part of 464a546 (I had the code lying around for several weeks but had not properly tested it yet).