add support for async mutex

Add support for async mutex for synchronizing coroutines/tasks using
sender receiver framework. Also, add lock_guard support which provides a
RAII wrapper for mutex to ow

add support for async mutex

Add support for async mutex for synchronizing coroutines/tasks using
sender receiver framework. Also, add lock_guard support which provides a
RAII wrapper for mutex to own it for the duration of a scoped block.

Tested: Add Unit Test using gtest
```
1/1 test_async_mutex OK 2.01s

Ok: 1
Expected Fail: 0
Fail: 0
Unexpected Pass: 0
Skipped: 0
Timeout: 0
```

Change-Id: I691528885a94b9cf55d4b7f2fb0c1e0e6d0ab84f
Signed-off-by: Jagpal Singh Gill <paligill@gmail.com>
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>

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