Suppress related warnings, fix nanoid, and get the build green (#7579)

This is in preparation for adding a Linux build step to our CI.

Release Notes:

- N/A

crates/gpui/src/platform/linux/dispatcher.rs

@@ -1,6 +1,8 @@
 #![allow(non_upper_case_globals)]
 #![allow(non_camel_case_types)]
 #![allow(non_snake_case)]
+//todo!(linux): remove
+#![allow(unused_variables)]
 
 use crate::{PlatformDispatcher, TaskLabel};
 use async_task::Runnable;

crates/gpui/src/platform/linux/text_system.rs

@@ -1,18 +1,12 @@
+//todo!(linux) remove
+#[allow(unused)]
 use crate::{
     Bounds, DevicePixels, Font, FontId, FontMetrics, FontRun, GlyphId, LineLayout, Pixels,
     PlatformTextSystem, RenderGlyphParams, SharedString, Size,
 };
 use anyhow::Result;
 use collections::HashMap;
-use font_kit::{
-    font::Font as FontKitFont,
-    handle::Handle,
-    hinting::HintingOptions,
-    metrics::Metrics,
-    properties::{Style as FontkitStyle, Weight as FontkitWeight},
-    source::SystemSource,
-    sources::mem::MemSource,
-};
+use font_kit::{font::Font as FontKitFont, source::SystemSource, sources::mem::MemSource};
 use parking_lot::RwLock;
 use smallvec::SmallVec;
 use std::borrow::Cow;

crates/gpui/src/platform/linux/window.rs

@@ -1,3 +1,6 @@
+//todo!(linux): remove
+#![allow(unused)]
+
 use super::BladeRenderer;
 use crate::{
     Bounds, GlobalPixels, LinuxDisplay, Pixels, PlatformDisplay, PlatformInputHandler,