[FEATURE] - Deployment multiple gdrive folders

[chrismclarke]

What?
Add support for providing multiple multiple google drive template and asset folders to sync data from as part of deployment config

Why?
Make it easier to deploy mulitple apps with some common sheets

How?
Deployment config currently uses the property google_drive.sheets_folder_id and google_drive.assets_folder_id

Either these could be extended to support an array of values, e.g.

google_drive:{
    sheets_folder_ids: ['folder_id_1', 'folder_id_2'] 
}

or could consider more generic config property, such as

data_sources: [
   { 
        provider:'google_drive',
        type:'sheets', 
        config:{id:'folder_id_1'}
    },
    { 
        provider:'google_drive',
        type:'sheets', 
        config:{id:'folder_id_2'}
    }
] 

Other details

• It would be more useful for users to be able to override individual flows detected in override folder even in cases where folder structures and filenames do not match (as the flow names do match), so will need to hold off merging/overriding flows until they have been extracted from sheets. No such problem for assets

• As this will require changes to various scripts may need to either wait post Refactor: Script dependencies #2061 or try to avoid too many conflicts

• Would be good to update overrides documentation to include info (and address use case [FEATURE] Data list overrides #1266)