Use a common backend for the explore assistant

[waziers]

Extension Framework Backend

• consolidated all the terraform into one folder
• use environment variables to trigger different behavior, no need to overwrite the variables files
• different modules for each backend
• improved .gitignore for terraform

Extension Examples

• Script to load examples into the database

Extension Cloud Function

• Remove all the examples.json, thelook files
• the cloud function presents the same interface as ML.GENERATE_TEXT, it takes in a prompt and parameters
• the script handles both local development and the Google Cloud Function deployment. It detects which configuration it should be in based on an environment variable

Extension Framework Javascript App

• load the examples, dimensions, measures from the extension instead of the cloud function
• remove the need for defining styles.d.ts by adding the typescript definition in the Globals.d.ts
• break up different react components into their own files (LandingPage, ExploreAssistant)
• use react-router for routing between pages
• associate the styles with each react components
• support SaSS for styles
• remove console.logs
• use primitives from the Looker Component library to match styling. Remove as much custom CSS as possible
• fix typescript errors
• store assistant state in redux store using redux toolkit. Since we're breaking up the react components, we need an easy way for them to work off the same state
• use dotenv for loading environment variables into webpack
• pick the backend based on the environment variables. The cloud function and the bigquery model use the same interface: prompt + parameters
• working bigquery backend that sends prompts through the connected model
• load examples from the bigquery backend

[LukaFontanilla]

@waziers, thank you for the awesome commit!

I just pushed a new commit to the branch with a few updates:

• There are certain browser features that can't be used in Looker Core (ie. browserRouter) so I migrated those to Core supported features
• I'd prefer to have folks install the extension with the stable GA release of Gemini and then opt into 1.5 if they want to. So everything was moved back to 1.0-pro-001 in both Cloud Function and terraform
• Updated the docs as they still had some old labels and instructions

[LukaFontanilla]

Everything looks great. Thank you for merging the updates for Core/docs and for adding the changelog ! LGTM 🎉