Invalid DumpGPU capture when ProjectDisplayedTitle contains special utf8 chars

Placing a special UTF-8 character into the "ProjectDisplayedTitle" will result in GPU dumps failing to open.

This appears to be because the dump will switch between us-ascii and UTF-16 file formats part-way through dumping …/<Dump>/Base/Passes.json, and then switch back.

This switch happens for Slate UI elements.

Representative GPU dumps are included in the test project.

1. Download the test project, and package Development Win64
2. Run the packaged project like normal, and execute the "DumpGPU" console command when the scene is open
3. Open the GPU Dump.
4. Observe the GPU Dump opens just fine.
5. Run the packaged project with the following command-line argument, including the "™" character: "-ini:Game:[/Script/EngineSettings.GeneralProjectSettings]:ProjectDisplayedTitle=Lyra™25"
6. Execute the "DumpGPU" command when the scene is open
7. Open the new GPU Dump.
8. Observe that the GPU Dump fails to load.
9. Diff the two …/<Dump>/Base/Passes.json files from the two GPU Dumps
10. Jump to the end of the JSON file. Observe the Event that should be named "ElementBatch", but is experiencing encoding issues in the second GPU Dump (Note: different diff programs will display different things, but it is null characters between each real character)

Uncaught SyntaxError: Unexpected non-whitespace character after JSON at position 343 (line 13 column 2)
at JSON.parse (<anonymous>)
at GPUDumpViewer.html:209:27
at Array.forEach (<anonymous>)
at load_json_dict_sequence (GPUDumpViewer.html:200:8)
at init_page (GPUDumpViewer.html:5763:13)
at onload (GPUDumpViewer.html:6594:158)