refactor: removing unnecessary pointers in context structure

[skosito]

Description

2 parts leftovers from discussions in PR: #1774

• add missing unit tests for zeta_core_context

• reduce pointers in config/coreContext/appContext

i think pointers should be removed when we want immutability as config, but also considered when there is large struct and mutability (as with core context) so i tried to remove pointers from config struct and also pass config around without pointers (this maybe can be revisited since config might be too big for this?)

Closes: #1807

Type of change

Refactor

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Include instructions and any relevant details so others can reproduce.

• Tested CCTX in localnet
• Tested in development environment
• Go unit tests
• Go integration tests
• Tested via GitHub Actions

Checklist:

• I have added unit tests that prove my fix feature works

[codecov]

Codecov Report

Attention: Patch coverage is 87.50000% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 45.11%. Comparing base (9aacfb7) to head (76ac1ef).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1831      +/-   ##
===========================================
+ Coverage    44.80%   45.11%   +0.31%     
===========================================
  Files          218      219       +1     
  Lines        12689    12779      +90     
===========================================
+ Hits          5685     5765      +80     
- Misses        6553     6561       +8     
- Partials       451      453       +2     

Files	Coverage Δ
zetaclient/core_context/zeta_core_context.go	88.88% <100.00%> (ø)
zetaclient/keys/keys.go	50.48% <100.00%> (ø)
zetaclient/tss/tss_signer.go	10.42% <0.00%> (ø)

[lumtis]

It's a good direction, I think it simplify the code not using pointer when unnecessary

[lumtis]

Looks good to me, just some comments on the changelogs