Implement DeletePersonalAccessToken RPC

[laushinka]

A user should be able to delete their PersonalAccessToken.

To do this, we need an API which can delete a token, given the supplied UUID of the token. When handling the RPC, we need to ensure that the Token UserID also matches the User of the request to prevent deletions of tokens for other users.

Acceptance Criteria:

• Implement DeletePersonalAccessToken in https://github.com/gitpod-io/gitpod/blob/main/components/public-api-server/pkg/apiv1/tokens.go#L146
• Ensure test coverage similar to existing token RPCs
• You will likely need to add a DB method to delete the token.
  • When deleting a token, only set the deleted property to true. This will ensure that db-sync performs the delete and sycnhronises