mm: (per market) enforce 1 bot configuration or allow/polish many

[norwnd]

I've noticed while there seems to be no restriction on how many bots I can make for a given market - configuring more than 1 results into unexpected behavior(s), eg:

• if you have 1 bot configured for DCR-USDC market
• and open a form to create a 2nd bot for that same DCR-USDC market, "delete" button shows on that form and if pressed it would delete the existing configuration 1 (rather than configuration 2 we are currently setting up)

I bet that's not the only issue present related to having many bots for the same market.

While it's probably OK to have many configurations for the same market by design, until it's well polished I'd suggest to restrict it to 1 bot per market (it's cleaner way to do it anyway because reconfiguring existing bot is pretty simple process (and we are paying the cost of navigating UI with many bots) - and all that variety is likely unnecessary for production uses, for testing though ... it might be desirable, but not at the cost of confusing a large user-base).