Add ability for GCV to render multiple tables as views

[rudokemper]

Work ongoing at https://github.com/ConservationMetrics/guardianconnector-views/tree/multiple-table-views

• [x] Implement and use an env var NUXT_ENV_TABLES with comma-separated table names.
• [x] Modify API to use dynamic routing for each table.
• [x] Turn map/ and gallery/ into dynamic pages.
• [x] Create index page at / route showing all of the available views.
• [x] Ensure Axios baseURL works for API requests in both yarn and Docker envs.
• [x] 404 handling for incorrect map/ and gallery/ routes
• [ ] Refactor env config to get front end filtering, hiding of unwanted columns, and mapbox maps to work with multiple tables