refactor(accountsdb): Add more testing for public API (#933)

Accompanied by some fixes, refactors, and helpful additions.
With this we are now testing insertion, deletion, forking, and behavior
of all these relative to the rooted slot.

Author: InKryption

src/accountsdb/account_store.zig

@@ -186,12 +186,12 @@ pub fn run(seed: u64, args: *std.process.ArgIterator) !void {
     // prealloc some references to use throught the fuzz
     try accounts_db.account_index.expandRefCapacity(1_000_000);
 
-    var manager_exit: std.atomic.Value(bool) = .init(false);
     var manager: sig.accounts_db.manager.Manager = try .init(allocator, &accounts_db, .{
-        .exit = &manager_exit,
-        .slots_per_full_snapshot = 50_000,
-        .slots_per_incremental_snapshot = 5_000,
-        .zstd_nb_workers = @intCast(std.Thread.getCpuCount() catch 0),
+        .snapshot = .{
+            .slots_per_full_snapshot = 50_000,
+            .slots_per_incremental_snapshot = 5_000,
+            .zstd_nb_workers = @intCast(std.Thread.getCpuCount() catch 0),
+        },
     });
     defer manager.deinit(allocator);
 
@@ -358,7 +358,10 @@ pub fn run(seed: u64, args: *std.process.ArgIterator) !void {
             random.int(u8) == 0;
         if (create_new_root) snapshot_validation: {
             largest_rooted_slot = @min(top_slot, largest_rooted_slot + 2);
-            accounts_db.largest_rooted_slot.store(largest_rooted_slot, .monotonic);
+            accounts_db.max_slots.set(.{
+                .rooted = largest_rooted_slot,
+                .flushed = null,
+            });
             try manager.manage(allocator);
 
             // holding the lock here means that the snapshot archive(s) wont be deleted