Having all the HIDL methods asynchronous, makes it hard for the
calling code to keep track of the operation status/result.
There are some operations which will generate asynchronous results (like
bgscan), convert all the other methods to synchronous methods.
The |EventCallback| objects will now just broadcast important events
(needed for other clients to listen for state changes). This will no
longer be used to send responses to every command sent to the HAL.
Bug: 32061909
Test: `./hardware/interfaces/update-makefiles.sh`
Change-Id: Id2433f4c8e028268dd027cdeb239ba4082b157b5
Changes in the CL:
1. Add missing docstring params in the HIDL interface.
2. Reword some method docs. Occurences of "will" is replaced
by "must" (based on comments received on supplicant HIDL interface:
go/aog/275115).
3. Add onFailure callbacks for all the methods and added docstrings for
them.
Bug: 31352200
Test: mmma -j32 hardware/interfaces/wifi/1.0
Change-Id: Ib7152625851023d6244f742bb77a8fdc0829e00d