Reapply "More aggressive using of cache on engine settings changes" (#4736)

* Reapply "More aggressive using of cache on engine settings changes (#4691)" (#4729)

This reverts commit 3f1f40eeba.

* Add a utility to get all the current values from the settings object

* Use an XState selector to get the latest settings snapshot for WASM

---------

Co-authored-by: Frank Noirot <frank@kittycad.io>

src/lib/settings/settingsUtils.test.ts

@@ -2,6 +2,7 @@ import { DeepPartial } from 'lib/types'
 import { Configuration } from 'wasm-lib/kcl/bindings/Configuration'
 import {
   configurationToSettingsPayload,
+  getAllCurrentSettings,
   projectConfigurationToSettingsPayload,
   setSettingsAtLevel,
 } from './settingsUtils'
@@ -65,3 +66,48 @@ describe(`testing settings initialization`, () => {
     expect(settings.app.themeColor.current).toBe('200')
   })
 })
+
+describe(`testing getAllCurrentSettings`, () => {
+  it(`returns the correct settings`, () => {
+    // Set up the settings
+    let settings = createSettings()
+    const appConfiguration: DeepPartial<Configuration> = {
+      settings: {
+        app: {
+          appearance: {
+            theme: 'dark',
+            color: 190,
+          },
+        },
+      },
+    }
+    const projectConfiguration: DeepPartial<Configuration> = {
+      settings: {
+        app: {
+          appearance: {
+            theme: 'light',
+            color: 200,
+          },
+        },
+        modeling: {
+          base_unit: 'ft',
+        },
+      },
+    }
+
+    const appSettingsPayload = configurationToSettingsPayload(appConfiguration)
+    const projectSettingsPayload =
+      projectConfigurationToSettingsPayload(projectConfiguration)
+
+    setSettingsAtLevel(settings, 'user', appSettingsPayload)
+    setSettingsAtLevel(settings, 'project', projectSettingsPayload)
+
+    // Now the test: get all the settings' current resolved values
+    const allCurrentSettings = getAllCurrentSettings(settings)
+    // This one gets the 'user'-level theme because it's ignored at the project level
+    // (see the test "doesn't read theme from project settings")
+    expect(allCurrentSettings.app.theme).toBe('dark')
+    expect(allCurrentSettings.app.themeColor).toBe('200')
+    expect(allCurrentSettings.modeling.defaultUnit).toBe('ft')
+  })
+})