Don't handle ED during router execution

[mrq1911]

If your trade route goes through insufficient assets that you don't hold already, you're charged 1.1 HDX to create an account, and then immediately when an asset is sold, you get 1 HDX refunded, making the swap 0.1 HDX more expensive technically.

Also, more rarely, if your trade amount is very small (or the ED of the asset is large), the execution can fail on the ED check of sufficient assets.

ED checks and fees should be ignored during the middle of router execution how to prevent this behavior. ED should still be handled correctly for the assets in and out of the route execution.