devtools-one-store cleanup

[cwstra]

Notable design changes to pavlobu's code:

• The original implementation kept the information for each tracked connection in separate maps; here, I've unified them
• Due to the above change, I also put the connection information into a small discriminated union, so Typescript can keep track of which case we're in.
• The original added a store property to each sub state, which seemed redundant, considering they're already keyed off of the store string. I removed it.

[pavlobu]

thanks, great job

Although I feel like we are having too many logic in one function, and it is really hard to unit test and maintain this.

It's not your or mine problem, the code was already written in this unmaintainable way without covering all edge cases with unit tests.

I think we need to apply some design patterns for the current devtoolsImpl function and split the code into smaller much easier to unit test pieces. That's seems to be like a long journey