Refactor to simplify and isolate chat communication workflow

[shruti0085]

Description of changes:
This change refactors the chat communication workflow to simplify and isolate responsibilities per class. This helps restrict access to certain components like browser and server to dedicated classes as defined below which in turn would help in improving testability. This design also helps easily add handling for more message types such as quick actions which returns ChatResult for rendering in the ChatUI.
Changes include:

• AmazonQViewActionHandler is now solely responsible for parsing and handling any actions that originate from within the WebView i.e messages from WebView/Chat UI.
• ChatCommunicationManager orchestrates handling communication between chat server and chat UI.
  • For requests to server, it takes the JSON object and converts it to the corresponding parameter Class and calls ChatMessageProvider.
  • For response received from server, it takes the response and invokes event to be sent to Chat UI
• AmazonQWebView is responsible for handling any interactions with the webview. It registers a listener ChatUiRequestListener for OnSendToChat event and sends message to webview for display.
• ChatMessage is the downstream layer responsbile for final communication with the AmazonQLSPServer. This class will ultimately also hold the encryption/decryption of request/response.
• ChatMessageProvider currently only wraps communication over to ChatMessage but eventually it will house more logic that would involve handling different types of messages eg. add tab/remove tab.
• ChatPartialResultMap has been simplified to hold a map of partial result token to tabIDs. Each chatMessage object is uniquely identified by it's tabId. If needed, this can also be further replaced in favor of direct access to the map in appropriate class.

Future refactors could further improve testability(unit tests) by changing singelton instance of these classes to interfaces.
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