A few size variables could be updated to `size_t` or `CF_ChunkSize_t`

[thnkslprpt]

Checklist

• [x] I reviewed the Contributing Guide.
• [x] I performed a cursory search to see if the bug report is relevant, not redundant, nor in conflict with other tickets.

Describe the bug A few variables in CF could be updated to the more expressive size_t or CF_ChunkSize_t types

Code snips val should be of CF_ChunkSize_t type: https://github.com/nasa/CF/blob/0f18ae4b8f800afefdf60c97809c737289f46942/fsw/src/cf_cmd.h#L475

size should be of size_t type: https://github.com/nasa/CF/blob/0f18ae4b8f800afefdf60c97809c737289f46942/fsw/src/cf_cmd.c#L942-L947

...and few others.

Expected behavior Update where appropriate

Reporter Info Avi Weiss @thnkslprpt