Provide upgrade/migration path from Protected Node

Looking at the codebase there are no migration plugins, so that means we'll need some work done:
* Source plugin for the Protected Node data.
* (probably) Process plugin to store or convert the data to the correct format.
* Migration YML file for mapping the source.
* Migration state file.

Hi,

@DamienMcKenna, thanks to open this issue.

Currently there is only an example module for people who wants/can do custom migrations: https://git.drupalcode.org/project/entity_access_password/-/tree/1.0.x/t...

Working on this.

While digging around the code I found that Protected Node uses hash('sha256') while EAP uses core's Password service which uses hash('sha512'). So I don't know if this will work :-\

My WIP. After realizing that the passwords can't be converted, I don't think there's any benefit to continuing on this?

Hi,

Thanks @DamienMcKenna for your work.

When doing EAP one year and a half ago, I tested if password could be reused as-it-is. And found out that D7 user account passwords worked on D9.

So that's why I made the following change on Protected Node. So with passwords saved from version 8.x-1.8 of Protected Node it works.

I forgot to include all the "use" statements in the module, so the migration review page would blow up. Or in fact probably everything would blow up. Oops.

Next steps:
* Migrate the password as-is, it'll either work or at least provide an indication that there *was* a password on the old site that then needs to be re-entered.
* Test =)
* Maybe write some test coverage.