Switch indexeddb backend to sqlite and improve IPC messaging (#38187)

- Use sqlite instead of heed. (one indexed database = one sqlite
database)
- Implement the backend for indexes
- Use keyranges where needed (as specified by the spec)
- Implement `getKey`
- Fix channel error messaging (led to a bunch of changes to how async
requests are handled)

Note: `components/net/indexeddb/engines/sqlite/serialize.rs` is unused;
I can delete it if needed.

Testing: Switching to sqlite eliminated many panics (exposing some new
failures).
Fixes: #38040

---------

Signed-off-by: Ashwin Naren <arihant2math@gmail.com>

components/net/indexeddb/engines/sqlite/object_data_model.rs

@@ -0,0 +1,32 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+use rusqlite::Row;
+use sea_query::Iden;
+
+#[derive(Iden)]
+pub enum Column {
+    Table,
+    ObjectStoreId,
+    Key,
+    Data,
+}
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct Model {
+    pub object_store_id: i32,
+    pub key: Vec<u8>,
+    pub data: Vec<u8>,
+}
+
+impl TryFrom<&Row<'_>> for Model {
+    type Error = rusqlite::Error;
+
+    fn try_from(value: &Row) -> Result<Self, Self::Error> {
+        Ok(Self {
+            object_store_id: value.get(0)?,
+            key: value.get(1)?,
+            data: value.get(2)?,
+        })
+    }
+}