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/net/resource_thread.rs

@@ -14,6 +14,7 @@ use std::sync::{Arc, Mutex, RwLock, Weak};
 use std::thread;
 use std::time::Duration;
 
+use base::generic_channel::GenericSender;
 use base::id::CookieStoreId;
 use cookie::Cookie;
 use crossbeam_channel::Sender;
@@ -112,7 +113,7 @@ pub fn new_resource_threads(
         protocols,
     );
     let idb: IpcSender<IndexedDBThreadMsg> = IndexedDBThreadFactory::new(config_dir.clone());
-    let storage: IpcSender<StorageThreadMsg> =
+    let storage: GenericSender<StorageThreadMsg> =
         StorageThreadFactory::new(config_dir, mem_profiler_chan);
     (
         ResourceThreads::new(public_core, storage.clone(), idb.clone()),