Embedded Resource link containing backslash encoded to %5C

### Expected behavior

If embedded resource URL contains backslash \ it should be converted automatically to forwardslash

### Actual behavior

Now, once the embedded resource URL contains backslash it is encoded to %5C, thus such a resource can't be downloaded.


### Steps to reproduce the problem

1. Create a simple HTML file that contains one link to JS file
`

Test

This is HTML page

`

2. Request page with HTTP Request with checked "Retrieve All Embedded Resources"


### JMeter Version

5.6.3

### Java Version

openjdk version "11.0.9" 2020-10-20 LTS

### OS Version

Microsoft Windows [Version 10.0.17763.6893]