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/components/screenSharePicker.css

@@ -17,6 +17,15 @@
     grid-template-columns: 1fr 1fr;
 }
 
+.vcd-screen-picker-settings-grid > div {
+    display: flex;
+    flex-direction: column;
+}
+
+.vcd-screen-picker-card {
+    flex-grow: 1;
+}
+
 .vcd-screen-picker-grid {
     display: grid;
     grid-template-columns: 1fr 1fr;
@@ -128,3 +137,10 @@
 .vcd-screen-picker-audio {
     margin-bottom: 0;
 }
+
+.vcd-screen-picker-hint-description {
+    color: var(--header-secondary);
+    font-size: 14px;
+    line-height: 20px;
+    font-weight: 400;
+}