Added EIP-2159 metrics

[OlegJakushkin]

following https://eips.ethereum.org/EIPS/eip-2159

Resolves #4842

Changes:

• added 4 new metrics that follow eip-2159 (ethereum_blockchain_height ethereum_best_known_block_number ethereum_peer_count ethereum_peer_limit)
• Added an attribute for developer defined metric name

Types of changes

• Bugfix (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)
• Documentation Update
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Other (please describe):

Testing

• [] Yes
• No

In case you checked yes, did you write tests??

• Yes
• No

We need to see how ethereum_best_known_block_number changes over time, will ask the Angkor team for that.

[OlegJakushkin]

Usage demo

Height:

Best known:

Compare block numbers:

peer_count vs limit:

[OlegJakushkin]

@LukaszRozmej: please review,
Also wanted to ask: in many places currently we update metrics not checking if Metrics are Enabled. Shall we update it everywhere to only update if the flag Metrics Enabled is set to true?

[LukaszRozmej]

@LukaszRozmej: please review, Also wanted to ask: in many places currently we update metrics not checking if Metrics are Enabled. Shall we update it everywhere to only update if the flag Metrics Enabled is set to true?

Would it be worth conditional jumps? Probably not.

[LukaszRozmej]

Fine overall, minor tweaks requested.