fix(flake.nix): synchronize playwright version in nix and package.json (#16715)

Ensure that the version of Playwright installed with the Nix flake is
equal to the one specified in `site/package.json.` -- This assertion
ensures that `pnpm playwright:install` will not attempt to download
newer browser versions not present in the Nix image, fixing the startup
script and reducing the startup time, as `pnpm playwright:install` will
not download or install anything.

We also pre-install the required Playwright web browsers in the dogfood
Dockerfile. This change prevents us from redownloading system
dependencies and Google Chrome each time a workspace starts.

Change-Id: I8cc78e842f7d0b1d2a90a4517a186a03636c5559
Signed-off-by: Thomas Kosiewski <tk@coder.com>

Signed-off-by: Thomas Kosiewski <tk@coder.com>

nix/docker.nix

@@ -50,10 +50,6 @@ let
     experimental-features = nix-command flakes
   '';
 
-  etcReleaseName = writeTextDir "etc/coderniximage-release" ''
-    0.0.0
-  '';
-
   etcPamdSudoFile = writeText "pam-sudo" ''
     # Allow root to bypass authentication (optional)
     auth      sufficient pam_rootok.so
@@ -115,6 +111,7 @@ let
       run ? null,
       maxLayers ? 100,
       uname ? "nixbld",
+      releaseName ? "0.0.0",
     }:
     assert lib.assertMsg (!(drv.drvAttrs.__structuredAttrs or false))
       "streamNixShellImage: Does not work with the derivation ${drv.name} because it uses __structuredAttrs";
@@ -207,6 +204,10 @@ let
         '';
       };
 
+      etcReleaseName = writeTextDir "etc/coderniximage-release" ''
+        ${releaseName}
+      '';
+
       # https://github.com/NixOS/nix/blob/2.8.0/src/libstore/globals.hh#L464-L465
       sandboxBuildDir = "/build";