R1:40720ab83d01

Expose initially set values of Maniphest custom date field and point values when removing them

Summary:
After removing or resetting a custom date field value or points value initially set at task creation there is no way to find and restore the previous value.
As Phorge adds a transaction entry anyway, include the previous value in the transaction title.
This makes it easier to revert an accidental removal of such data and is also more aligned with the behavior of other custom field types.

Closes T15846…