feature (dot/network): add CLI flag --node-key, hex encoded libp2p node key

[edwardmack]

Changes

This PR introduces code that implements CLI flag --node-key which allows the user to pass in the secret Ed25519 key to use for libp2p networking. The value is parsed as a hex-encoded Ed25519 secret key, i.e. 64 hex characters. The node then uses that key for libp2p networking. Warning, secrets provided as command-line arguments are easily exposed, so use of this option should be limited to development and testing. This was introduced to enable setting this key in a manner that is used by ZombieNet (https://github.com/paritytech/zombienet) testing framework.

Issues

Work done researching issue #2843.

Primary Reviewer

@timwu20

[codecov]

Codecov Report

Merging #3043 (7bbed01) into development (c57ade6) will increase coverage by 0.01%.
The diff coverage is 0.00%.

Additional details and impacted files

@@               Coverage Diff               @@
##           development    #3043      +/-   ##
===============================================
+ Coverage        51.42%   51.43%   +0.01%     
===============================================
  Files              219      219              
  Lines            28009    28025      +16     
===============================================
+ Hits             14403    14415      +12     
- Misses           12320    12323       +3     
- Partials          1286     1287       +1     

[edwardmack]

Closing this PR because code for this PR was implemented in PR #3098.