governor: support multiple stakers

[moodysalem]

in the governor we need to support migration to improved staker contracts. the governor needs to be able to point to multiple staker contracts and add utilize voting weights from any of them.

e.g. you can specify any 'allowed' staker address when voting, and then voters can vote with all of the allowed stakers for which they have staked tokens

keep the old methods so that the contract is backwards compatible by using the current staker as a default staker

[Benjtalkshow]

Hello @moodysalem
Can i give this a try. Since it is labelled good first issue i believe i can handle it

[baitcode]

@moodysalem
I'd like to take this issue.

I would:

• Add staker addresses into new proposal config field.
• Update proposal config version in Governor constructor
• Change vote function flow if new proposal config appears and stakers field is filled

[moodysalem]

Accepted @baitcode

Interesting to put it into config, I was imagining the governor would have a mapping. I generally avoid storing arrays, what would the benefit be of putting it in config? I don't think there is a big advantage to removing the old versions, for example

@moodysalem I'd like to take this issue.

I would:

• Add staker addresses into new proposal config field.
• Update proposal config version in Governor constructor
• Change vote function flow if new proposal config appears and stakers field is filled