feat: Batch NXM withdrawals

[roxdanila]

Context

Closes https://github.com/NexusMutual/smart-contracts/issues/1173

Add TokenController.withdrawNXM to withdraw all NXM from the platform. The caller must do the checks if the NXM is withdrawable and modify params accordingly to skip / include specific NXM withdrawals.

Changes proposed in this pull request

• Assessment
  • add unstakeForAll
  • convert requires to custom error
  • remove redundant isMember check in withdrawRewardsTo
• TokenController
  • add withdrawNXM
  • add _withdrawClaimAssessmentTokensForUser internal function
  • remove withdrawPendingRewards in favour of withdrawNXM

Test plan

• integration tests
• fork tests

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)
• [x] 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
• [x] 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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• :rocket: = Feedback

[rackstar]

There is an edge case where the user might be prevented from withdrawing available rewards. If user has expired stake / claimable rewards for a tranche but has locked NXM for governance.

• withdrawNXM is hardcoded to always withdraw both stake and rewards,
• withdraw stake will fail since user has locked NXM for governance, this will effectively block the user from withdrawing available rewards as it will revert.
• there is no option for them to skip stake and only claim rewards in this scenario
• user will have to wait for gov lock to expire before they can withdraw rewards

https://github.com/NexusMutual/smart-contracts/blob/release-candidate/contracts/modules/staking/StakingPool.sol#L554

I guess, waiting for gov lock to expire is not a big deal. but wanted to flag this scenario in any case

@shark0der @roxdanila @MilGard91

[rackstar]

marking as draft so it won't be accidentally merged while on audit