feat(netconf-proto): add global YANG module cache

[riccardo-negri]

Add YangModuleCache, a thread-safe cache of raw module texts shared by all SSH sessions so get_yang_module skips redundant get-schema RPCs for a given (name, revision). Only versioned modules are cached; values are stored as Arc<str> for cheap hits. Exposes hit/miss/size counters via OTel, and renames YangSchemaFormat -> GetSchemaFormat per RFC 6022.

[Copilot]

Pull request overview

Introduces a globally shared, thread-safe YANG module text cache in netconf-proto and wires it through the NETCONF SSH client and YANG push caching pipeline so repeated (module name, revision) fetches can avoid redundant get-schema RPCs. Also renames the NETCONF monitoring “format” enum to align terminology with RFC 6022.

Changes:

• Added YangModuleCache (shared across SSH sessions) and integrated it into NetConfSshClient::get_yang_module.
• Plumbed the shared cache through the collector → yang-push cache actor/fetcher and exposed cache hit/miss/size metrics via OTel callbacks.
• Renamed YangSchemaFormat to GetSchemaFormat in the NETCONF protocol layer.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
crates/yang-push/src/cache/fetcher.rs	Injects a shared YangModuleCache into per-session NETCONF connect configs.
crates/yang-push/src/cache/actor.rs	Registers OTel observable instruments that read YangModuleCache atomic stats.
crates/netconf-proto/src/yang_module_cache.rs	Adds the new global cache implementation + unit tests and exposed stats.
crates/netconf-proto/src/protocol.rs	Renames schema format enum to GetSchemaFormat and updates (de)serialization.
crates/netconf-proto/src/lib.rs	Exposes the new yang_module_cache module publicly.
crates/netconf-proto/src/client.rs	Adds module cache plumbing to connect/client and implements cached get_yang_module.
crates/collector/src/lib.rs	Creates a single shared cache instance and passes it into the yang-push cache actor/fetcher.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[ustorbeck]

why concatenating the strings to create the key?
better use them in a tuple instead, that's more robust:

type ModuleCacheKey = (String, String);
fn make_key(name: &str, revision: &str) -> ModuleCacheKey {
    (name.to_owned(), revision.to_owned())
}