Standalone editor: Remove more dependencies

[JiuqingSong]

Remove more dependencies to old code to get ready for standalone editor. Including

Entity delimiter related functions

• getDelimiterFromElement: Create a replacement function isEntityDelimiter in roosterjs-content-model-dom
• addDelimiters: Create a copy in roosterjs-content-model-dom

Metadata related functions

• validate: Create a copy in roosterjs-content-model-dom
• create*Definition: Create a copy in roosterjs-content-model-dom
• Definition: Create a copy in roosterjs-content-model-types
• DefinitionType: Create a new type in roosterjs-content-model-types, use string literal type instead of const enum

Other DOM utilities

• wrap: Create a copy in roosterjs-content-model-dom
• unwrap: Create a copy in roosterjs-content-model-dom