Name snapshots consistently (#19346)

#### Problem

Snapshot names are overloaded, and there are multiple terms that mean the same thing. This is confusing. Here's a list of ones in the codebase that I've found:

```
- snapshot_dir
- snapshots_dir
- snapshot_path
- snapshot_output_dir
- snapshot_package_output_path
- snapshot_archives_dir
```

#### Summary of Changes

For all the ones that are about the directory where snapshot archives are stored, ensure they are `snapshot_archives_dir`. For the ones about the (bank) snapshots directory, set to `bank_snapshots_dir`.


Co-authored-by: Michael Vines <mvines@gmail.com>

ledger/src/bank_forks_utils.rs

@@ -42,15 +42,15 @@ pub fn load(
 ) -> LoadResult {
     if let Some(snapshot_config) = snapshot_config {
         info!(
-            "Initializing snapshot path: {}",
-            snapshot_config.snapshot_path.display()
+            "Initializing bank snapshot path: {}",
+            snapshot_config.bank_snapshots_dir.display()
         );
-        let _ = fs::remove_dir_all(&snapshot_config.snapshot_path);
-        fs::create_dir_all(&snapshot_config.snapshot_path)
+        let _ = fs::remove_dir_all(&snapshot_config.bank_snapshots_dir);
+        fs::create_dir_all(&snapshot_config.bank_snapshots_dir)
             .expect("Couldn't create snapshot directory");
 
         if snapshot_utils::get_highest_full_snapshot_archive_info(
-            &snapshot_config.snapshot_package_output_path,
+            &snapshot_config.snapshot_archives_dir,
         )
         .is_some()
         {
@@ -118,8 +118,8 @@ fn load_from_snapshot(
     }
 
     let (deserialized_bank, timings) = snapshot_utils::bank_from_latest_snapshot_archives(
-        &snapshot_config.snapshot_path,
-        &snapshot_config.snapshot_package_output_path,
+        &snapshot_config.bank_snapshots_dir,
+        &snapshot_config.snapshot_archives_dir,
         &account_paths,
         &process_options.frozen_accounts,
         genesis_config,