Fix captured let/const in 'for' condition or incrementer

[rbuckton]

This fixes a failure to propagate changes to a captured for variable declaration in a converted loop body when the declaration is captured in the condition or incrementer of the for statement.

Fixes #45598

[andrewbranch]

Don’t forget to close out #45675. Thanks @Reaphook for raising the issue and a good attempt at fixing it 👍