feat: clean up p2p & implement bootnode (seed peers) support

[zivkovicmilos]

Description

This PR introduces bootnode (seed mode) support for TM2 peering, and cleans up parts of the p2p module codebase.

Closes #2308

Contributors' checklist...

• Added new tests, or not needed, or not feasible
• Provided an example (e.g. screenshot) to aid review or the PR is self-explanatory
• Updated the official documentation or not needed
• No breaking changes were made, or a BREAKING CHANGE: xxx message was included in the description
• Added references to related issues and PRs
• Provided any useful hints for running manual tests
• Added new benchmarks to generated graphs, if any. More info here.

[codecov]

Codecov Report

Attention: Patch coverage is 65.51724% with 10 lines in your changes missing coverage. Please review.

Project coverage is 60.89%. Comparing base (ca9eb4b) to head (8536074).
Report is 27 commits behind head on master.

Files with missing lines	Patch %	Lines
tm2/pkg/p2p/key.go	70.83%	4 Missing and 3 partials ⚠️
tm2/pkg/crypto/ed25519/ed25519.go	0.00%	2 Missing ⚠️
tm2/pkg/crypto/crypto.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2852      +/-   ##
==========================================
- Coverage   60.91%   60.89%   -0.02%     
==========================================
  Files         564      563       -1     
  Lines       75267    74693     -574     
==========================================
- Hits        45849    45487     -362     
+ Misses      26047    25856     -191     
+ Partials     3371     3350      -21     

Flag	Coverage Δ
contribs/gnofaucet	14.46% <ø> (ø)
misc/genstd	80.54% <ø> (ø)
misc/logos	19.88% <ø> (-0.36%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.