feat: active filter subscription management for edge nodes
## Subscription Manager
* edgeFilterSubLoop reconciles desired vs actual filter subscriptions
* edgeFilterHealthLoop pings filter peers, evicts stale ones
* EdgeFilterSubState per-shard tracking of confirmed peers and health
* best-effort unsubscribe on peer removal
* RequestEdgeShardHealth and RequestEdgeFilterPeerCount broker providers
## WakuNode
* Remove old edge health loop (loopEdgeHealth, edgeHealthEvent, calculateEdgeTopicHealth)
* Register MessageSeenEvent push handler on filter client during start
* startDeliveryService now returns `Result[void, string]` and propagates errors
## Health Monitor
* getFilterClientHealth queries RequestEdgeFilterPeerCount via broker
* Shard/content health providers fall back to RequestEdgeShardHealth when relay inactive
* Listen to EventShardTopicHealthChange for health recalculation
* Add missing return p.notReady() on failed edge filter peer count request
* HealthyThreshold constant moved to `connection_status.nim`
## Broker types
* RequestEdgeShardHealth, RequestEdgeFilterPeerCount request types
* EventShardTopicHealthChange event type
## Filter Client
* Add timeout parameter to ping proc
## Tests
* Health monitor event tests with per-node lockNewGlobalBrokerContext
* Edge (light client) health update test
* Edge health driven by confirmed filter subscriptions test
* API subscription tests: sub/receive, failover, peer replacement
Co-authored-by: Ivan FB <128452529+Ivansete-status@users.noreply.github.com>
Co-authored by Zoltan Nagy
* Introduce api/send
Added events and requests for support.
Reworked delivery_monitor into a featured devlivery_service, that
- supports relay publish and lightpush depending on configuration but with fallback options
- if available and configured it utilizes store api to confirm message delivery
- emits message delivery events accordingly
prepare for use in api_example
* Fix edge mode config and test added
* Fix some import issues, start and stop waku shall not throw exception but return with result properly
* Utlize sync RequestBroker, adapt to non-async broker usage and gcsafe where appropriate, removed leftover
* add api_example app to examples2
* Adapt after merge from master
* Adapt code for using broker context
* Fix brokerCtx settings for all usedbrokers, cover locked node init
* Various fixes upon test failures. Added initial of subscribe API and auto-subscribe for send api
* More test added
* Fix multi propagate event emit, fix fail send test case
* Fix rebase
* Fix PushMessageHandlers in tests
* adapt libwaku to api changes
* Fix relay test by adapting publish return error in case NoPeersToPublish
* Addressing all remaining review findings. Removed leftovers. Fixed loggings and typos
* Fix rln relay broker, missed brokerCtx
* Fix rest relay test failed, due to publish will fail if no peer avail
* ignore anvil test state file
* Make terst_wakunode_rln_relay broker context aware to fix
* Fix waku rln tests by having them broker context aware
* fix typo in test_app.nim
