Replace relevant services logic with a function suite.
Adds HasAllRelevantServices and GetRelevantServices, which check
This changes the following:
- Removes nRelevantServices from CConnman, disconnecting it a bit more from protocol-level logic.
- This has the added benefit of removing nServicesExpected from CNode - instead letting net_processing's VERSION message handling simply check HasAllRelevantServices.
- In order to prevent this change from preventing connection to -connect= nodes which do not have the require flags, -connect nodes are now given the "addnode" flag. This also allows outbound connections to !NODE_NETWORK nodes for -connect nodes (which was already true of addnodes).
- Has the (somewhat unintended) consequence of changing one of the eviction metrics from the same metric to requiring HasRelevantServices.
This should make NODE_NETWORK_LIMITED much simpler to implement.
- Rename fAddnode to a more-descriptive "manual_connection"
- Clarify docs for requirements/handling of addnode/connect nodes
- Switch DNSSeed-needed metric to any-automatic-nodes, not services
This is a backport of core PR11456
Reviewers: #bitcoin_abc, schancel
Reviewed By: #bitcoin_abc, schancel
Subscribers: schancel, teamcity
Differential Revision: https://reviews.bitcoinabc.org/D1760