Feature request: Add a new unique as "Cancel [policy] adopted"

[AutumnPizazz]

Before creating

• This is NOT a gameplay feature from Civ VI, BNW, or outside - see Roadmap
• This is NOT a gameplay feature from Vanilla Civ V or from G&K - If so, it should be a comment in Missing features from Civ V - G&K #4697

Problem Description

It has been issued in #3242 , but I have to hand it up here as I need it rapidly.
Guess it may be done easily so is it okay in next version? NEED HELP!

Related Issue Links

No response

Desired Solution

Nothing.

Alternative Approaches

Nothing.

Additional Context

No response

[SomeTroglodyte]

... how exactly would this relate to the pool of accumulated culture and the calculation how much is needed for the next one?

[AutumnPizazz]

I have little regard for the cost of policy progress. If it must be considered, the suggestion is to cancel a policy that has been implemented and then recalculate (or refresh) the cultural expenditure required for the next policy.