* basic contract work for 'decrease_pledge' functionality
note: it doesn't yet return tokens back to the operator
* returning extra tokens after decreasing pledge
* added vesting message to track pledge decrease
* attaching the track message when processing delegation decrease
* checking for zero value request
* fixed event test
* allowing to decrease pledge from the vesting contract
* integration test for the feature
* reorganised the integration tests
* updated nyxd client traits
* wallet support
* typescript helpers
* moved 'pledge more' functionality to operator commands
* cli commands for decreasing pledge
* changed error variant to make clippy happier
* removed unused import
* eslint
* fixed post-rebase imports
* added cargo config
* added PendingMixNodeChanges to MixNodeDetails
* returning event id after creating it
* Streamlined getting mixnode details by identity key
* setting pending pledge changes on increase/decrease
* clearing the value on resolving the event
* checking for correct invariants when clearing events
* further pending events unit tests fixes
* new unit tests for tx endpoints
* queries for pending events (by id)
* migration code
* using default value for pending changes if unavailable
* improved integration test assertions
Jędrzej Stuczyński