fix: delegation root node bug when switching identities

[Dudleyneedham]

fixes https://github.com/KILTprotocol/ticket/issues/620

When creating a Delegation root node switching accounts would not re-render the new account.

How to test:

Create a new delegation and switch accounts.

Checklist:

• I have verified that the code works
• I have verified that the code is easy to understand
  • If not, I have left a well-balanced amount of inline comments
• I have left the code in a better state
• I have documented the changes (where applicable)

[rflechtner]

Works! As a suggestion: seems to me that we don't have to create & save a delegation in state before hitting the "submit" button (execting submit()). The whole switching identities process could be a lot leaner if we only create the delegation on submit and otherwise take the identity (owner) from the props.