Cooperative settlement

[palango]

User Story

As Chris, I want to cooperatively settle my channels when possible, so that I save time and money.

Acceptance criteria

• Cooperative settlement implemented in the SDK
• Cooperative settlement added to the CLI
• Cooperative settlement added to the dApp

Tasks

• Create sub-issues to track progress of the implementation in the sub-components
• Update contracts to a version with cooperative settlement (see Cooperative settlement raiden-contracts#1474)
• Implement sub-component changes
• Adapt e2e tests to include cooperative settlement

Resources

• Cooperative settlement raiden-contracts#1474
• https://hackmd.io/1_MkYDcZQaem_r6dkJ0LHg?both
• https://github.com/raiden-network/team/issues/938

[taleldayekh]

Close when #2850 #2876 are finalised.