Fix nasa#137, separated increment and decrement operators from other operators in fsw/src/lc_action.c and lc_watch.c except when using POP_RPN_DATA

[myc-yang]

Checklist (Please check before submitting)

• I reviewed the Contributing Guide.
• I signed and emailed the appropriate Contributor License Agreement to GSFC-SoftwareRelease@mail.nasa.gov and copied cfs-program@lists.nasa.gov.

Describe the contribution
Fixes #137

Testing performed
Re-ran LC unit tests.

Expected behavior changes
No impact to behavior

System(s) tested on

• Hardware: [e.g. PC, SP0, MCP750]
• OS: [e.g. Ubuntu 18.04, RTEMS 4.11, VxWorks 6.9]
• Versions: [e.g. cFE 6.6, OSAL 4.2, PSP 1.3 for mcp750, any related apps or tools]

Additional context
Add any other context about the contribution here.

Third party code
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Contributor Info - All information REQUIRED for consideration of pull request
Michael Yang / NASA/GSFC

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