Fix #494, add missing stub functions for OSAL API

[jphickey]

Describe the contribution
Did a quick scrub for public OSAL APIs defined in libosal.a but not defined in stub library.

Added stub functions for:

OS_TaskFindIdBySystemData()
OS_FileSysAddFixedMap()
OS_TimedRead()
OS_TimedWrite()
OS_FileSysAddFixedMap()

Required for testing other modules that use these functions. Also correct a name mismatch issue in OS_TaskGetInfo().

Fixes #494

Testing performed
Build and run all unit tests.

Expected behavior changes
No change to behavior or FSW. Just adds stubs for future use.

System(s) tested on
Ubuntu 20.04

Additional context
These were not actively used anywhere yet (otherwise would be a link failure) but likely to become an issue as PSP coverage tests are implemented.

Contributor Info - All information REQUIRED for consideration of pull request
Joseph Hickey, Vantage Systems, Inc.

[jphickey]

Note - commit b6b1ad8 corrects a copy/paste issue with task_id output of OS_TaskFindIdBySystemData stub - should be filling the buffer not a pointer to buffer.