chore(nix): update xorg attributes to top-level (#2037)

## Description

Recent updates to `nixpkgs` (unstable) have deprecated the `xorg`
package set in favor of top-level package names. This PR updates the FHS
development shell dependencies in `flake.nix` to eliminate evaluation
warnings when running `nix develop .#fhs`.

**Changes:**
Replaced the deprecated `xorg.*` attributes with their new top-level
names inside the Electron FHS environment:

* `xorg.libX11` $\rightarrow$ `libx11`
* `xorg.libXcomposite` $\rightarrow$ `libxcomposite`
* `xorg.libXdamage` $\rightarrow$ `libxdamage`
* `xorg.libXext` $\rightarrow$ `libxext`
* `xorg.libXfixes` $\rightarrow$ `libxfixes`
* `xorg.libXrandr` $\rightarrow$ `libxrandr`
* `xorg.libxcb` $\rightarrow$ `libxcb`
* `xorg.libXcursor` $\rightarrow$ `libxcursor`
* `xorg.libXi` $\rightarrow$ `libxi`
* `xorg.libXtst` $\rightarrow$ `libxtst`

## Linked Issues

None.

## Additional Context

None.

flake.lock

@@ -2,11 +2,11 @@
   "nodes": {
     "nixpkgs": {
       "locked": {
-        "lastModified": 1780243769,
-        "narHash": "sha256-x5UQuRsH3MqI0U9afaXSNqzTPSeZlRLvFAav2Ux1pNw=",
+        "lastModified": 1783224372,
+        "narHash": "sha256-8i/87eeoqiGE4yOTjwSA3Eh/ziJRQEmd/unYU+K27sk=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "331800de5053fcebacf6813adb5db9c9dca22a0c",
+        "rev": "d407951447dcd00442e97087bf374aad70c04cea",
         "type": "github"
       },
       "original": {

flake.nix

@@ -72,16 +72,17 @@
                   at-spi2-core
                   cups.lib # libcups.so.2 is in 'lib' output, not 'out'
                   libdrm
-                  xorg.libX11
-                  xorg.libXcomposite
-                  xorg.libXdamage
-                  xorg.libXext
-                  xorg.libXfixes
-                  xorg.libXrandr
-                  xorg.libxcb
-                  xorg.libXcursor
-                  xorg.libXi
-                  xorg.libXtst
+                  libx11
+                  libxcomposite
+                  libxdamage
+                  libxext
+                  libxfixes
+                  libxrandr
+                  libxcb
+                  libxcursor
+                  libxi
+                  libxt
+                  libxtst
                   expat
                   libxkbcommon
                   libgbm # libgbm.so.1 is now a separate package from mesa