Exclude rust-analyzer.server.path from VS Code's sync feature

By changing the scope of this configuration to `machine-overridible`,
this setting becomes fully local for the VS Code instance the user is
running.

Having this setting excluded from syncing should help avoid
inconveniences for users who have VS Code installed on two different
operating systems, where the paths to the language server binary would
very likely mismatch.

Author: brainplot

editors/code/package.json

@@ -326,6 +326,7 @@
                         "null",
                         "string"
                     ],
+                    "scope": "machine-overridable",
                     "default": null,
                     "markdownDescription": "Path to rust-analyzer executable (points to bundled binary by default). If this is set, then `#rust-analyzer.updates.channel#` setting is not used"
                 },