Add await and Protocol to the identifiers escaping rules (#88)

### Motivation

Resolves #34

### Modifications

- Added `Protocol` to the keywords set.
- Added `await` to the keywords set.

### Result

- Would be able to support `Protocol` and `await` as property names.

### Test Plan

Tested and verified for both names. They are properly renamed to
`_Protocol` and `_await`

Author: denil-ct

Sources/_OpenAPIGeneratorCore/Extensions/String.swift

@@ -217,5 +217,7 @@ fileprivate extension String {
         "Array",
         "Type",
         "type",
+        "Protocol",
+        "await",
     ]
 }