Feature: multi pool router

[danoctavian]

Context

Add support for using multiple pools to allocate capacity for a cover.

Issue: https://github.com/NexusMutual/cover-router/issues/25

Changes proposed in this pull request

Add a new function that takes as input the requested cover amount and the set of staking pools that can be used.

Use a greedy allocation approach to find the best pools to allocate to, keeping in mind, price does not follow a linear function past 90% capacity, so it can't be as simple as sorting pools by base price and allocate until you fill it up etc.

Full details on this approach are in the RFC:

https://www.notion.so/nxmcommunity/RFC-Multi-pool-cover-router-e4a1637910be49268cb52c5fb9fbe21d

Test plan

Write unit tests for the computation and the parts dependant on it |(quoteEngine.js)

Checklist

• [x] Rebased the base branch
• [x] Attached corresponding Github issue
• [x] Prefixed the name with the type of change (i.e. feat, chore, test)
• [ ] Performed a self-review of my own code
• [x] Followed the style guidelines of this project
• [x] Made corresponding changes to the documentation
• [x] Didn't generate new warnings
• [ ] Didn't generate failures on existing tests
• [x] Added tests that prove my fix is effective or that my feature works

Review

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[danoctavian]

fixed all tests except 1.

Fairly satisfied with the coverage but i want to think of more edge cases

[shark0der]

Toyed around with the implementation here: https://github.com/NexusMutual/cover-router/pull/33 Feel free to borrow stuff from it or work directly on top of it. FYI it's a very much wip and probably fails to run, but should be close to its final form.