[EMSUSD-3783] "Load Sublayer" doesn't respect windows paths "\"

**Describe the bug**
When pasting a windows path into the "Load Sublayers" dialog, the backslashes are escaped rather than treated as path separators

**Steps to reproduce**
1. Right click on a layer in Layer Editor and choose "Load Sublayers..."
2. Paste a standard windows path with backslashes (eg `C:\Autodesk\cube.usd`)
3. Observe the path reference is invalid and the backslashes have been removed

**Expected behavior**
Expected the "\\" in the path to be conformed to "/" if that is what USD requires. Alternatively would have expected the standard maya file browser dialog

**Attachments**

**Specs (if applicable):**
- Windows 11
- Maya 2024
- maya_usd 0.35