[core] Rename entity_types.inc to entity_types.h

Neither PlatformIO nor ESP-IDF/CMake copy .inc files to the build
directory. Rename to .h so it's recognized by both build systems.
Exempt from pragma-once lint since this file is intentionally included
multiple times with different macro definitions.

script/ci-custom.py

@@ -672,7 +672,7 @@ def lint_using_esp_idf_deprecated(fname, line, col, content):
     )
 
 
-@lint_content_check(include=["*.h"])
+@lint_content_check(include=["*.h"], exclude=["esphome/core/entity_types.h"])
 def lint_pragma_once(fname, content):
     if "#pragma once" not in content:
         return (