feat: simplify up-scoping or down-scoping of scopes overwriteAccessTokenScopes()

[yuriyz]

Description

With UpdateTokenType script we can do up-scoping or down-scoping tokens. However it can be not trivial to code the script. We should introduce context.overwriteAccessTokenScopes("<new scopes>").

Scatch of code that would have to be written without it

 def modifyAccessToken(self, accessToken, context):
        previousGrant = context.getGrant()
        originalScopes = previousGrant.getScopes()

        # overwrite scope
        context.getAccessTokenEntity().setScope("myscope")
        accessToken.setCode("<regenerate JWT here if it is AT as JWT>");
        return True

[yuriyz]

Done.