Cancel the new post resets the state of form

When user is creating new post and then cancel it
the data remains in the form which appears when we
click on new post again. The state of form should
be reset.

TNL-148
Merge pull request #5032 from mlkwaqas/waqas/tnl148-reset-newpost-form-on-cancel

Forums new post form should reset state when user cancels