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/create.rs

@@ -0,0 +1,59 @@
+/* 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/. */
+
+pub(crate) fn create_tables(conn: &rusqlite::Connection) -> Result<(), rusqlite::Error> {
+    conn.execute(
+        r#"create table database
+(
+    name    varchar          not null
+        primary key,
+    origin  varchar          not null,
+    version bigint default 0 not null
+);"#,
+        [],
+    )?;
+
+    conn.execute(
+        r#"create table object_store
+(
+    id             integer               not null
+        primary key autoincrement,
+    name           varchar               not null
+        unique,
+    key_path       varbinary_blob,
+    auto_increment boolean default FALSE not null
+);"#,
+        [],
+    )?;
+
+    conn.execute(
+        r#"create table object_data
+(
+    object_store_id integer not null
+        references object_store,
+    key             blob    not null,
+    data            blob    not null,
+    constraint "pk-object_data"
+        primary key (object_store_id, key)
+);"#,
+        [],
+    )?;
+
+    conn.execute(
+        r#"create table object_store_index
+            (
+                id                integer        not null
+                primary key autoincrement,
+                object_store_id   integer        not null
+                references object_store,
+                name              varchar        not null
+                unique,
+                key_path          varbinary_blob not null,
+                unique_index      boolean        not null,
+                multi_entry_index boolean        not null
+            );"#,
+        [],
+    )?;
+    Ok(())
+}