Fix nasa/CF#334, Temporary files possible filename conflict

[lkebulad]

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
Modified the creation of temporary filenames in function CF_CFDP_R_Init() to have the name of the file be defined as the concatenation of the source entity ID and the sequence number to avoid filename conflicts.

Fixes issue #334

Testing performed

1. git clone cFS repo
2. cd cFS
3. git submodule init
4. git submodule update
5. git clone CF repo into cFS/apps directory
6. rename CF to cf
7. git submodule init
8. git submodule update
9. go back to cFS directory
10. cp cfe/cmake/Makefile.sample Makefile
11. cp -r cfe/cmake/sample_defs sample_defs
12. In "sample_defs/targets.cmake", add cf to this line to make it look like this: list(APPEND MISSION_GLOBAL_APPLIST sample_app sample_lib cf)
13. make SIMULATION=native ENABLE_UNIT_TESTS=true BUILDTYPE=debug OMIT_DEPRECATED=true prep
14. in "sample_defs/cpu1_cfe_es_startup.scr" add cf to first line line this:
    CFE_APP, cf, CF_AppMain, CF, 80, 16384, 0x0, 0;
15. make install
16. make test

Expected behavior changes
Temporary filenames created via CF_CFDP_R_Init() should now have filenames be a concatenation of their source entity ID and sequence number

System(s) tested on
Ubuntu 20.04.6

Contributor Info - All information REQUIRED for consideration of pull request
Lukas Kebuladze, GSFC

[keegan-moore]

Looks like this colon is causing issues for some platforms (vxworks).
There was a suggestion to use an underscore (_) instead.
Working to find a path to update this.

[keegan-moore]

Potentially looking to update it within this MR:

• Issue: Segfault trying to dereference NULL pointer. #435
• PR: Fix #435, simplify state machines and add holdover #480
• Related PR Comment: https://github.com/nasa/CF/pull/480/files#r2474984536