*: better locking

[pinebit]

Summary:

1. dkg and edit commands use 4.relay.obol.dev as default relay. The list is to be updated later when a backup relay is added.
2. Previous lock implementation removed the lock file upon application exit, this is now changed to not remove the lock file, as we need to a) remember the timestamp, b) pass the lock to edit commands. The must be no impact to the existing charon run or charon dkg behavior.
3. dkg used locking unconditionally, there is no option to disable locking for dkg.
4. Unlike dkg, charon run requires --private-key-file-lock to be set, which now defaults to true in LCDVN. Still, run has ability to disable locking protection, whereas dkg does not.
5. The current lock update period is 1s, the lease period is 5s. This means if you restart charon (run or dkg) faster than 5s, the boot will be blocked and the process exits with the corresponding message.
6. The locking is expected to work across run and dkg.

category: refactor
ticket: #4242

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

❌ Patch coverage is 62.50000% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.67%. Comparing base (f9042d5) to head (0920116).
⚠️ Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
dkg/dkg.go	42.85%	2 Missing and 2 partials ⚠️
app/privkeylock/privkeylock.go	50.00%	0 Missing and 2 partials ⚠️
cmd/createcluster.go	0.00%	0 Missing and 1 partial ⚠️
cmd/dkg.go	0.00%	1 Missing ⚠️
cmd/testall.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4255      +/-   ##
==========================================
- Coverage   56.91%   56.67%   -0.25%     
==========================================
  Files         237      237              
  Lines       31004    31304     +300     
==========================================
+ Hits        17646    17741      +95     
- Misses      11108    11290     +182     
- Partials     2250     2273      +23     

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