refactor: cctx validate outbound

[skosito]

Description

Check issue and specs. Mostly moving code around and trying to move some common parts in subfunctions (marked in comments with some questions). Also modified tests accordingly.

Closes: #2278

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

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

All modified and coverable lines are covered by tests ✅

Project coverage is 68.72%. Comparing base (f5a7aae) to head (3a7cf12).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2317      +/-   ##
===========================================
- Coverage    68.74%   68.72%   -0.02%     
===========================================
  Files          302      302              
  Lines        19180    19168      -12     
===========================================
- Hits         13186    13174      -12     
  Misses        5347     5347              
  Partials       647      647              

Files	Coverage Δ
x/crosschain/keeper/cctx_gateway_observers.go	100.00% <ø> (ø)
x/crosschain/keeper/cctx_gateway_zevm.go	100.00% <100.00%> (ø)
...hain/keeper/cctx_orchestrator_validate_outbound.go	94.92% <100.00%> (ø)
x/crosschain/keeper/initiate_outbound.go	100.00% <100.00%> (ø)
x/crosschain/keeper/msg_server_vote_outbound_tx.go	92.78% <100.00%> (ø)

[github-actions]

!!!WARNING!!!
nosec detected in the following files: x/crosschain/keeper/cctx_orchestrator_validate_outbound.go

Be very careful about using #nosec in code. It can be a quick way to suppress security warnings and move forward with development, it should be employed with caution. Suppressing warnings with #nosec can hide potentially serious vulnerabilities. Only use #nosec when you're absolutely certain that the security issue is either a false positive or has been mitigated in another way.

Only suppress a single rule (or a specific set of rules) within a section of code, while continuing to scan for other problems. To do this, you can list the rule(s) to be suppressed within the #nosec annotation, e.g: /* #nosec G401 */ or //#nosec G201 G202 G203
Broad #nosec annotations should be avoided, as they can hide other vulnerabilities. The CI will block you from merging this PR until you remove #nosec annotations that do not target specific rules.

Pay extra attention to the way #nosec is being used in the files listed above.

[lumtis]

I think this is a good direction. I would like to explore later the possibility of consolidating more observer/evm functions

[kingpinXD]

lgtm , left a minor comment