mining: detailed dashboard for p2pool

[rssoc]

This PR implements a long requested community feature intended to educate newcomers on mining concepts and expose them to p2pool.

This adds:

• A New Dashboard View: Accessible from "Advanced > Mining" when "P2Pool" is selected as the mining mode. Implements buttons with transitions and theme compatibility, as well as a user interface and experience matching the rest of the program.
• Educational Resources: An on-demand explanation for each dashboard field to help educate newcomers on p2pool and mining terminology and concepts.
• Refined Data Visualization: Friendly readouts for hashrate, with rolling averages, and mining effort, alongside an "Advanced" section for those who wish to view the raw API data.
• Synchronization Gating: Waits until the side and blockchains are synced to address some consistency issues. The initial synchronization takes some time, and the reporting from the API is a bit eager since we're using P2Pools built-in miner which itself doesn't wait.

This is intended to supersede #4182 which was a partial implementation lacking most of the important points above.

Screenshots