Support Hypercore LTS Version 10

[ttiurani]

This PR adds support for the current v10 version of hypercore.

With the v9 => v10 upgrade, the Javascript hypercore changed dramatically. This caused this PR to balloon quite massively, but alas, there was no other way to do the needed changes than with one big swoop.

This PR was enabled by recent new versions of:

• random-access-storage
• random-access-memory
• random-access-disk
• flat-tree
• compact-encoding

There is a related branch in hypercore-protocol-rs with changes that add wire protocol support.

In addition to v9 to v10 port, this PR adds:

• WASM support
• Support for both tokio and async-std as runtimes
• Clearing entries from hypercore
• Github Actions as CI