feat: Fully use protobuf, fix controller issues and cleanup (#305)

## Description
### First commit
Restructured protobuf schemas to make them easier to use across
languages, switched to using them in-place of JSON for signaling as
well, so there's no 2 different message formats flying about. Few new
message types to deal with clients and nestri-servers better (not final
format, may see changes still).

General cleanup of dead/unused code along some bug squashing and package
updates.

TODO for future commits:
- [x] Fix additional controllers not doing inputs (possibly needs
vimputti changes)
- [x] ~~Restructure relay protocols code a bit, to reduce bloatiness of
the currently single file for them, more code re-use.~~
- Gonna keep this PR somewhat manageable without poking more at relay..
- [x] ~~Try to fix issue where with multiple clients, static stream
content causes video to freeze until there's some movement.~~
- Was caused by server tuned profile being `throughput-performance`,
causing CPU latency to be too high.
- [x] Ponder the orb


### Second + third commit
Redid the controller polling handling and fixed multi-controller
handling in vimputti and nestri code sides. Remove some dead relay code
as well to clean up the protocol source file, we'll revisit the meshing
functionality later.

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* Added software rendering option and MangoHud runtime config;
controller sessions now support reconnection and batched state updates
with persistent session IDs.

* **Bug Fixes**
* Restored previously-filtered NES-like gamepads so they connect
correctly.

* **Chores**
* Modernized dependencies and protobuf tooling, migrated to
protobuf-based messaging and streaming, and removed obsolete CUDA build
steps.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Co-authored-by: DatCaptainHorse <DatCaptainHorse@users.noreply.github.com>

packages/configs/MangoHud/MangoHud.conf

@@ -0,0 +1,48 @@
+legacy_layout=false
+
+# common
+horizontal
+horizontal_stretch
+hud_no_margin
+no_small_font
+background_alpha=0.66
+round_corners=0
+background_color=000000
+font_size=24
+position=top-left
+engine_short_names
+
+# colors
+text_color=DFDFDF
+gpu_color=FF4E00
+cpu_color=00AA00
+engine_color=00AA00
+vram_color=00AA00
+ram_color=00AA00
+frametime_color=FF4E00
+
+# load colors
+cpu_load_color=DFDFDF,DF964D,DF3D3D
+gpu_load_color=DFDFDF,DF964D,DF3D3D
+
+# GPU and VRAM
+gpu_text=NESTRI
+gpu_stats
+gpu_load_change
+gpu_load_value=70,90
+
+vram
+
+# CPU and RAM
+cpu_text=CPU
+cpu_stats
+cpu_load_change
+cpu_load_value=70,90
+
+ram
+
+# FPS and timing
+fps
+fps_metrics=0.01
+
+frame_timing