[macOS] Stream artificially limited to 90fps when set to 120fps in Moonlight

Nobody has claimed this yet.

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Is your issue described in the documentation?

- [x] I have read the documentation

### Is your issue present in the latest beta/pre-release?

- [x] This issue is present in the nightly release

### Describe the Bug

I have a tablet (Samsung Tab S9+) capable of 120hz refresh rate on which I run Moonlight.
Connecting it to my Macbook Pro M1 host works but the fps does not reach 120fps. Instead, it stays at a steady 90 fps.


### Expected Behavior

The macOS Sunshine host provides 120fps when the client requests it.

### Additional Context

Troubleshooting done:
- I have successfuly used the full 120Hz of the tablet when connected to a Windows Sunshine host
- I tried on both the native and external display of the macOS host
- I made sure Moonlight is set to request 120fps
- I made sure Sunshine exposes 120fps (although I don't think this matters here)
- I made sure the display I tried to stream from is set to 120Hz

### Host Operating System

macOS

### Operating System Version

Sonoma 14.5

### Architecture

arm

### Sunshine commit or version

v2024.621.193854

### Package

macOS - Homebrew

### GPU Type

n/a

### GPU Model

N/A

### GPU Driver/Mesa Version

N/A

### Capture Method

None

### Config

```Shell
output_name = 3
hevc_mode = 2
fps = [30,60,90,120]
resolutions = [
1280x720,
1920x1080,
2560x1440,
1920x1200,
2560x1600,
1280x800
]
origin_web_ui_allowed = pc
```

### Apps

_No response_

### Relevant log output

```shell
[2024:06:23:03:10:37]: Info: // Testing for available encoders, this may generate errors. You can safely ignore those errors. //
[2024:06:23:03:10:37]: Info: Trying encoder [videotoolbox]
[2024:06:23:03:10:37]: Info: Detecting displays
[2024:06:23:03:10:37]: Info: Detected display: Built-in Retina Display (id: 1) connected: true
[2024:06:23:03:10:37]: Info: Detected display: 28E850 (id: 3) connected: true
[2024:06:23:03:10:37]: Info: Configuring selected display (3) to stream
[2024:06:23:03:10:37]: Info: SDR color coding [Rec. 601]
[2024:06:23:03:10:37]: Info: Color depth: 8-bit
[2024:06:23:03:10:37]: Info: Color range: [JPEG]
[2024:06:23:03:10:37]: Warning: [h264_videotoolbox @ 0x107b2df90] PrioritizeEncodingSpeedOverQuality property is not supported on this device. Ignoring.
[2024:06:23:03:10:37]: Info: [h264_videotoolbox @ 0x107b2df90] This device does not support the AllowOpenGop option. Value ignored.
[2024:06:23:03:10:37]: Info: SDR color coding [Rec. 601]
[2024:06:23:03:10:37]: Info: Color depth: 8-bit
[2024:06:23:03:10:37]: Info: Color range: [JPEG]
[2024:06:23:03:10:37]: Info: SDR color coding [Rec. 601]
[2024:06:23:03:10:37]: Info: Color depth: 8-bit
[2024:06:23:03:10:37]: Info: Color range: [JPEG]
[2024:06:23:03:10:37]: Error: Couldn't open [av1_videotoolbox]
[2024:06:23:03:10:37]: Info: Detecting displays
[2024:06:23:03:10:37]: Info: Detected display: Built-in Retina Display (id: 1) connected: true
[2024:06:23:03:10:37]: Info: Detected display: 28E850 (id: 3) connected: true
[2024:06:23:03:10:37]: Info: Configuring selected display (3) to stream
[2024:06:23:03:10:37]: Info: SDR color coding [Rec. 709]
[2024:06:23:03:10:37]: Info: Color depth: 10-bit
[2024:06:23:03:10:37]: Info: Color range: [JPEG]
[2024:06:23:03:10:38]: Info:
[2024:06:23:03:10:38]: Info: // Ignore any errors mentioned above, they are not relevant. //
[2024:06:23:03:10:38]: Info:
[2024:06:23:03:10:38]: Info: Found H.264 encoder: h264_videotoolbox [videotoolbox]
[2024:06:23:03:10:38]: Info: Found HEVC encoder: hevc_videotoolbox [videotoolbox]
[2024:06:23:03:10:38]: Info: Executing [Desktop]
[2024:06:23:03:10:38]: Info: CLIENT CONNECTED
[2024:06:23:03:10:38]: Info: Detecting displays
[2024:06:23:03:10:38]: Info: Detected display: Built-in Retina Display (id: 1) connected: true
[2024:06:23:03:10:38]: Info: Detected display: 28E850 (id: 3) connected: true
[2024:06:23:03:10:38]: Info: Configuring selected display (3) to stream
[2024:06:23:03:10:38]: Info: SDR color coding [Rec. 709]
[2024:06:23:03:10:38]: Info: Color depth: 8-bit
[2024:06:23:03:10:38]: Info: Color range: [MPEG]
[2024:06:23:03:10:38]: Error: opening microphone '' failed. Please set a valid input source in the Sunshine config.
[2024:06:23:03:10:38]: Error: Available inputs:
[2024:06:23:03:10:38]: Error: MacBook Pro Microphone
[2024:06:23:03:10:38]: Error: Unable to initialize audio capture. The stream will not have audio.
```

The issue provides no source file or test entry point. Start by reproducing the macOS host stream with a 120 Hz display and Moonlight configured for 120 fps, then trace the macOS display and frame-timing path. Done means the stream reaches the requested 120 fps rather than remaining at 90 fps.

Written by the indexing model from the issue text.