feat(plugins): deliver batched filesystem events (#2049)

Closes #1948

Plugins receive debounced batches of files created, changed and removed outside the editor in open projects, as SDK `Event::FilesChanged` (delivered through `other("files-changed", …)`, so released WIT is unchanged), under the `events` capability and the plugin's path filters. Activation on these events requires API 1.3. Batches are coalesced per plugin through its actor, survive cancellation without losing deltas, and are dropped when the project or host shuts down.

Co-authored-by: arnaud-ritti <[email protected]>

plugins/official/string-tools/Cargo.lock

@@ -98,6 +98,8 @@ checksum = "cf8baf1c55e62ffcace7a9f06f4bd9cd3f0c4beb022d3b367256b91b87513d98"
 name = "openidea-plugin"
 version = "0.1.0"
 dependencies = [
+ "serde",
+ "serde_json",
  "wit-bindgen",
 ]
 
@@ -149,6 +151,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4148590afebada386688f18773da617792bf2ef03ffc1e4cbd2b1d45b023e0ba"
 dependencies = [
  "serde_core",
+ "serde_derive",
 ]
 
 [[package]]