Apply signaling component

[ActoryOu]

Issue #, if available:

What was changed?

• Add Signaling component and coreJSON as external projects, and update Signaling code to call APIs of component.

Why was it changed?

• To apply Signaling re-factoring component into dev branch. Signaling component is separated out as independent library. And coreJSON is used in Signaling component.

How was it changed?

• Add Signaling component and coreJSON as external projects, import it via ExternalProject_Add, and update Signaling code to call APIs of component.

What testing was done for the changes?

• Verified master demo on Ubuntu
• Verified webrtc_client_test and pass all test cases.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 96.09121% with 12 lines in your changes missing coverage. Please review.

Project coverage is 88.60%. Comparing base (98188ff) to head (edb6fde).
Report is 1 commits behind head on develop.

❗ Current head edb6fde differs from pull request most recent head 280e1f0

Please upload reports for the commit 280e1f0 to get more accurate results.

Files	Patch %	Lines
src/source/Signaling/LwsApiCalls.c	96.27%	11 Missing ⚠️
src/source/Sctp/Sctp.c	50.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1950      +/-   ##
===========================================
- Coverage    88.65%   88.60%   -0.06%     
===========================================
  Files           48       48              
  Lines        12711    12662      -49     
===========================================
- Hits         11269    11219      -50     
- Misses        1442     1443       +1     

☔ View full report in Codecov by Sentry.
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[MushMal]

A high-level review. Most comments are about the conventions. The main concern would be the amount of churn in a highly-sensitive API which has a high-level re-entrant driver code.

[ActoryOu]

Thanks @MushMal for review! I'd like to update after signaling library.

[ActoryOu]

Hi @MushMal,
Please help check if all comments are handled/answered if you have some time.

Thank you.

[ActoryOu]

Closing this PR because it's unable to merge commits from develop branch. #2020 is the re-create PR.