bot: Separate markdown from classification generation

[joncinque]

Problem

Markdown and epoch classification output are tied together, but the stake pool's mainnet run needs the stake pool testnet classification. At the same time, we don't want to clobber the markdown generated by the not-a-stake-pool run.

Solution

Add an --epoch-classification flag, which works exactly the same way as the markdown flag, allowing for more fine-grained control over epoch classification output.

[joncinque]

Merging to run a test, post-merge review will be very welcome if possible!

[t-nelson]

lgtm. is it time to just kill markdown output? the sfdp website should be a better experience and AFAIK the markdown is so large that the github wiki won't render it in most cases

[joncinque]

is it time to just kill markdown output? the sfdp website should be a better experience and AFAIK the markdown is so large that the github wiki won't render it in most cases

that makes sense to me. maybe @danpaul000 or @mvines have an opinion on this too