VPL: h264 encoding is broken due to IDR frame insertion

## Description
The Windows VPL encoder currently forces the HEVC codec if H264 is selected due to a known issue when trying to insert IDR frames. Current consensus is that #3051 will be merged without this being fixed in order to get the new encoder to Windows VR Gamers using Intel ARCs more quickly.

A comment is left in `VideoEncoderVPL.cpp` with a similar error description.

## General Troubleshooting
- [x] I carefully followed the instructions in the [README](https://github.com/alvr-org/ALVR/blob/master/README.md) and successfully completed the setup wizard
- [x] I read the [ALVR GitHub Wiki](https://github.com/alvr-org/ALVR/wiki)

## Environment

### Hardware
**CPU**:
_not relevant_

**GPU**:
Intel ARC B580

**GPU Driver Version**:
_unknown_

**Audio**:
_not relevant_

### Installation
**ALVR Version**:
master branch using this PR: #3051

**ALVR Settings File**:
h264 codec selected

**SteamVR Version**:
_not relevant_

**Install Type**:
- [ ] Packaged (`exe`, `deb`, `rpm`, etc)
- [ ] Portable (`zip`)
- [x] Source

**OS Name and Version**:
Windows 11