rewrite block explorer in React

[nickorIow]

When the block explorer was initially written, we were still using the CavCash.Node software with the hacky TCP server and it was easier to just use Blazor when doing TCP comms. Re-write should make requests to nodes directly from the client.

Re-write should also focus on having a nice design. When I wrote CavCash.Blockexplore, it was made solely because I got tired of reading JSON so I didn't spend nearly any time on styling.