feat(search): support indexing same field multiple times with different configurations (redis#3157)

Allow RediSearchSchema to accept an array of field definitions for a single field,
enabling the same field to be indexed with different types and aliases.

Example:
```typescript
{
  sku: [
    { type: SCHEMA_FIELD_TYPE.TEXT, AS: 'sku_text' },
    { type: SCHEMA_FIELD_TYPE.TAG, AS: 'sku_tag', SORTABLE: true }
  ]
}
```

- Add SchemaFieldDefinition type for reusable field type union
- Update RediSearchSchema to accept SchemaFieldDefinition | SchemaFieldDefinition[]
- Update parseSchema to normalize input and iterate over field definition arrays

---

- fix typo in PT SCHEMA_TEXT_FIELD_PHONETIC

- Add JSDoc and README documentation for the new array syntax that allows
indexing the same field multiple times with different types or aliases.

Author: nkaradzhov

packages/search/README.md

@@ -32,6 +32,24 @@ await client.ft.create('idx:animals', {
 
 See the [`FT.CREATE` documentation](https://redis.io/commands/ft.create/#description) for information about the different field types and additional options.
 
+#### Indexing a Field Multiple Times
+
+You can index the same field multiple times with different types or aliases by using an array:
+
+```javascript
+await client.ft.create('idx:products', {
+  sku: [
+    { type: SCHEMA_FIELD_TYPE.TEXT, AS: 'sku_text' },
+    { type: SCHEMA_FIELD_TYPE.TAG, AS: 'sku_tag', SORTABLE: true }
+  ]
+}, {
+  ON: 'HASH',
+  PREFIX: 'product:'
+});
+```
+
+This allows querying the same field using different search strategies.
+
 #### Querying the Index
 
 Once we've created an index, and added some data to Redis hashes whose keys begin with the prefix `noderedis:animals`, we can start writing some search queries.  RediSearch supports a rich query syntax for full-text search, faceted search, aggregation and more.  Check out the [`FT.SEARCH` documentation](https://redis.io/commands/ft.search) and the [query syntax reference](https://redis.io/docs/interact/search-and-query/query) for more information.

packages/search/lib/commands/CREATE.spec.ts

@@ -332,6 +332,28 @@ describe('FT.CREATE', () => {
           ['FT.CREATE', 'index', 'SCHEMA', 'field', 'TEXT', 'INDEXMISSING']
         );
       });
+
+      it('same field indexed twice with different aliases and types', () => {
+        assert.deepEqual(
+          parseArgs(CREATE, 'idx', {
+            sku: [
+              {
+                type: SCHEMA_FIELD_TYPE.TEXT,
+                AS: 'sku_text'
+              },
+              {
+                type: SCHEMA_FIELD_TYPE.TAG,
+                AS: 'sku_tag',
+                SORTABLE: true
+              }
+            ]
+          }, {
+            ON: 'HASH',
+            PREFIX: 'blog:post:'
+          }),
+          ['FT.CREATE', 'idx', 'ON', 'HASH', 'PREFIX', '1', 'blog:post:', 'SCHEMA', 'sku', 'AS', 'sku_text', 'TEXT', 'sku', 'AS', 'sku_tag', 'TAG', 'SORTABLE']
+        );
+      });
     });
 
     it('with ON', () => {