Add amendments page and enable features based on a amendments

[ckniffen]

This is a two parter:

• Page to show enabled amendments
• Show/hide relevant functionality on the Explorer based on whether it's available (e.g. NFTs)

Currently features like NFTs are enabled by checking an environment variable (see). Instead when the site loads a call needs to be made to find out which amendments are enabled on the network.

The query is https://xrpl.org/websocket-api-tool.html?server=wss%3A%2F%2Fs.altnet.rippletest.net%3A51233%2F&req=%7B%22id%22%3A3%2C%22command%22%3A%22ledger_entry%22%2C%22index%22%3A%227DB0788C020F02780A673DC74757F23823FA3014C1866E72CC4CD8B226CD6EF4%22%2C%22ledger_index%22%3A%22validated%22%7D

The page will then used that cached data to display which amendments are enabled on the network.