overhaul & improve Linux screenshare (#489)

Fixes fps/resolution not properly being applied
Enables hardware encoding via vaapi
Redesigns stream picker modal 

Co-authored-by: kaitlynkittyy <kaitlynyaadev@kaitlynyaa.dev>
Co-authored-by: Oleh Polisan <polisanoleg@gmail.com>
Co-authored-by: Vendicated <vendicated@riseup.net>

src/renderer/patches/screenShareFixes.ts

@@ -0,0 +1,69 @@
+/*
+ * SPDX-License-Identifier: GPL-3.0
+ * Vesktop, a desktop app aiming to give you a snappier Discord Experience
+ * Copyright (c) 2023 Vendicated and Vencord contributors
+ */
+
+import { Logger } from "@vencord/types/utils";
+import { currentSettings } from "renderer/components/ScreenSharePicker";
+import { isLinux } from "renderer/utils";
+
+const logger = new Logger("VesktopStreamFixes");
+
+if (isLinux) {
+    const original = navigator.mediaDevices.getDisplayMedia;
+
+    async function getVirtmic() {
+        try {
+            const devices = await navigator.mediaDevices.enumerateDevices();
+            const audioDevice = devices.find(({ label }) => label === "vencord-screen-share");
+            return audioDevice?.deviceId;
+        } catch (error) {
+            return null;
+        }
+    }
+
+    navigator.mediaDevices.getDisplayMedia = async function (opts) {
+        const stream = await original.call(this, opts);
+        const id = await getVirtmic();
+
+        const frameRate = Number(currentSettings?.fps);
+        const height = Number(currentSettings?.resolution);
+        const width = Math.round(height * (16 / 9));
+        const track = stream.getVideoTracks()[0];
+
+        track.contentHint = String(currentSettings?.contentHint);
+
+        const constraints = {
+            ...track.getConstraints(),
+            frameRate,
+            width: { min: 640, ideal: width, max: width },
+            height: { min: 480, ideal: height, max: height },
+            advanced: [{ width: width, height: height }],
+            resizeMode: "none"
+        };
+
+        track
+            .applyConstraints(constraints)
+            .then(() => {
+                logger.info("Applied constraints successfully. New constraints: ", track.getConstraints());
+            })
+            .catch(e => logger.error("Failed to apply constraints.", e));
+
+        if (id) {
+            const audio = await navigator.mediaDevices.getUserMedia({
+                audio: {
+                    deviceId: {
+                        exact: id
+                    },
+                    autoGainControl: false,
+                    echoCancellation: false,
+                    noiseSuppression: false
+                }
+            });
+            audio.getAudioTracks().forEach(t => stream.addTrack(t));
+        }
+
+        return stream;
+    };
+}