[PS-2096] BEEEEP: Add Psono importer (#4286)

* Add psono json importer

Create types for psono export format
Add test files
Write tests for psono-json-importer
Write importer for psono export
Register 'psonojson' with `importOptions`
Import/register psono-json-importer with import.service
Add instructions on how to export from Psono

* Retain all imported data

Ensure all data is retained by adding unmapped properties into custom fields
Each item type has a set of mapped properties, anything not matching will be created as a custom field
Write extensive tests to ensure data is present

* Skipping GPG

We currently cannot import GPG Keys into notes or custom fields

* Add organizational test

Verify that folders get converted to collections when imported by an org

* Remove combined test-file (whole export)

* Remove redundant null type

libs/common/spec/importers/test-data/psono-json/empty-folders.ts

@@ -0,0 +1,10 @@
+import { PsonoJsonExport } from "@bitwarden/common/importers/psono/psono-json-types";
+
+export const EmptyTestFolderData: PsonoJsonExport = {
+  folders: [
+    {
+      name: "EmptyFolder",
+      items: [],
+    },
+  ],
+};