fix(config): wire up `Provider.Enabled` flag (#10804)

* fix(config): explicit Provider.Enabled flag

Adds missing config option described in
https://github.com/ipfs/kubo/issues/10803

* refactor: remove Experimental.StrategicProviding

removing experiment, replaced with Provider.Enabled

* test(cli): routing [re]provide

updated and added tests for manually triggering provide and reprovide
and making them respect global configuration flag to avoid
inconsistent behaviors

* docs: improve DelegatedRouters

* refactor: default DefaultProviderWorkerCount=16

- simplified default for both
- 16 is safer for non-accelerated DHT client
- acceletated DHT performs better without limit anyway - updated docs

(cherry picked from commit 2ab3f58c)