(core) Update dependencies

Summary:
Changes the minimum version of Node to 18, and updates the Docker images and GitHub workflows to build Grist with Node 18.

Also updates various dependencies and scripts to support building running tests with arm64 builds of Node.

Test Plan: Existing tests.

Reviewers: paulfitz

Reviewed By: paulfitz

Differential Revision: https://phab.getgrist.com/D3968

app/plugin/grist-plugin-api.ts

@@ -243,6 +243,15 @@ async function getMappingsIfChanged(data: any): Promise<WidgetColumnMap|null> {
   return _mappingsCache ? JSON.parse(JSON.stringify(_mappingsCache)) : null;
 }
 
+/**
+ * Used by tests to wait for all pending requests to settle.
+ *
+ * TODO: currently only waits for requests for mappings.
+ */
+export async function testWaitForPendingRequests() {
+  return await _activeRefreshReq;
+}
+
 /**
  * Renames columns in the result using columns mapping configuration passed in ready method.
  * Returns null if not all required columns were mapped or not widget doesn't support