sync build-on-save ZLS options

`enableBuildOnSave` needs to be explicitly set to `null` otherwise it defaults back to `false`.

package.json

@@ -177,14 +177,14 @@
         "zig.zls.enableBuildOnSave": {
           "scope": "resource",
           "type": "boolean",
-          "description": "Whether to enable build-on-save diagnostics",
-          "default": false
+          "description": "Whether to enable build-on-save diagnostics. Will be automatically enabled if the `build.zig` has declared a 'check' step.",
+          "default": null
         },
-        "zig.zls.buildOnSaveStep": {
+        "zig.zls.buildOnSaveArgs": {
           "scope": "resource",
-          "type": "string",
-          "description": "Select which step should be executed on build-on-save",
-          "default": "install"
+          "type": "array",
+          "description": "Specify which arguments should be passed to Zig when running build-on-save.\n\nIf the `build.zig` has declared a 'check' step, it will be preferred over the default 'install' step.",
+          "default": []
         },
         "zig.zls.enableAutofix": {
           "scope": "resource",
@@ -273,25 +273,29 @@
           "scope": "resource",
           "type": "string",
           "description": "Path to 'builtin;' useful for debugging, automatically set if let null",
-          "format": "path"
+          "format": "path",
+          "default": null
         },
         "zig.zls.zigLibPath": {
           "scope": "resource",
           "type": "string",
           "description": "Zig library path, e.g. `/path/to/zig/lib/zig`, used to analyze std library imports",
-          "format": "path"
+          "format": "path",
+          "default": null
         },
         "zig.zls.buildRunnerPath": {
           "scope": "resource",
           "type": "string",
           "description": "Path to the `build_runner.zig` file provided by ZLS. null is equivalent to `${executable_directory}/build_runner.zig`",
-          "format": "path"
+          "format": "path",
+          "default": null
         },
         "zig.zls.globalCachePath": {
           "scope": "resource",
           "type": "string",
           "description": "Path to a directory that will be used as zig's cache. null is equivalent to `${KnownFolders.Cache}/zls`",
-          "format": "path"
+          "format": "path",
+          "default": null
         },
         "zig.zls.completionLabelDetails": {
           "scope": "resource",