feat: Added metric for concurrent keysigns

[kevinssgh]

Description

1. Keysign manager was added to keep track of outbound signature attempts
2. A new metric was integrated to export the number of active signatures.

Closes: #1604

Type of change

• New feature (non-breaking change which adds functionality)

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

/usr/local/bin # curl localhost:8886/metrics | grep zetaclient_num_active_message_signs
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 18048    0 18048    0     0  7861k      0 --:--:-- --:--:-- --:--:-- 8812k
# HELP zetaclient_num_active_message_signs Number of concurrent key signs
# TYPE zetaclient_num_active_message_signs gauge
zetaclient_num_active_message_signs 4

Checklist:

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

[github-actions]

!!!WARNING!!!
nosec detected in the following files: zetaclient/tss/tss_signer.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.

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[codecov]

Codecov Report

Attention: Patch coverage is 60.60606% with 13 lines in your changes are missing coverage. Please review.

Project coverage is 52.01%. Comparing base (0759af2) to head (ca62d41).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1954      +/-   ##
===========================================
+ Coverage    51.96%   52.01%   +0.04%     
===========================================
  Files          234      235       +1     
  Lines        13355    13382      +27     
===========================================
+ Hits          6940     6960      +20     
- Misses        5980     5987       +7     
  Partials       435      435              

Files	Coverage Δ
zetaclient/metrics/metrics.go	77.77% <ø> (ø)
zetaclient/tss/tss_keysign_manager.go	100.00% <100.00%> (ø)
zetaclient/tss/tss_signer.go	10.22% <0.00%> (-0.21%)	⬇️

[kingpinXD]

lgtm , left a minor comment

[lumtis]

@kevinssgh can we target the branch to v16.0.0? to include it in the next release

[skosito]

just couple small comments and questions

[kevinssgh]

@kevinssgh can we target the branch to v16.0.0? to include it in the next release

#1960