Verify VPP: core implementation (#30295)

# Checklist for submitter

If some of the following don't apply, delete the relevant line.

<!-- Note that API documentation changes are now addressed by the
product design team. -->

- [x] Changes file added for user-visible changes in `changes/`,
`orbit/changes/` or `ee/fleetd-chrome/changes`.
See [Changes
files](https://github.com/fleetdm/fleet/blob/main/docs/Contributing/guides/committing-changes.md#changes-files)
for more information.
- [x] Input data is properly validated, `SELECT *` is avoided, SQL
injection is prevented (using placeholders for values in statements)
- For database migrations:
- [x] Ensured the correct collation is explicitly set for character
columns (`COLLATE utf8mb4_unicode_ci`).
- [x] Added/updated automated tests
- [x] Manual QA for all new/changed functionality

changes/29830-verify-vpp-db-migration

@@ -0,0 +1 @@
+- Adds functionality for verifying installation of VPP apps.