Port StorageThreadMsg to GenericChannel (#38932)

This change includes the following additions to GenericChannel:
- Add a GenericSend trait which is meant to replace the `IpcSend` trait
over time, as channels are migrated. For the time being this means, that
we often need to use `GenericSend::send()` to disambiguate from the
`IpcSend::send` function, until all usages of `IpcSend` have been
replaced.
- Add an OpaqueSender impl for GenericSender
- Add a profiled version of GenericChannel. The profiling is 1:1 the
same as for the existing profiled IPC channel, namely that only the
blocked time during `recv` is measured.


Testing: No functional changes, covered by existing tests
Part of #38912

---------

Signed-off-by: Jonathan Schwender <schwenderjonathan@gmail.com>

components/constellation/constellation.rs

@@ -2631,10 +2631,10 @@ where
         }
 
         debug!("Exiting storage resource threads.");
-        if let Err(e) = self
-            .public_resource_threads
-            .send(StorageThreadMsg::Exit(storage_ipc_sender))
-        {
+        if let Err(e) = generic_channel::GenericSend::send(
+            &self.public_resource_threads,
+            StorageThreadMsg::Exit(storage_ipc_sender),
+        ) {
             warn!("Exit storage thread failed ({})", e);
         }