Replace di-live with default Debian installer and leverage default Debian Live support

[JedMeister]

Beyond the specific issue/feature noted in the subject, this is a meta-issue covering other install related bugs/issues.

Once the relevant Debian components (debian installer, debian live, etc) are integrated into TurnKey and this issue is closed, it should (or at least hopefully) also address the following issues:

• support for di-live preseeding #149
• Full filesystem encryption option on install #166
• Di-live support for UEFI install #1435
• [ISO install] on VMware products fails to autodetect where to install grub #1456
• di-live - LVM - install loop if you change your mind #1490

Preliminary work has already been done by @a3s7p - see https://github.com/a3s7p/tklive & internal testing is in progress. Once complete, "rc" builds of Core and Lamp will be published (perhaps others?). The anticipated ISO naming for v18.x based builds will include uefi in the name to differentiate from the current v18.x builds. E.g.

turnkey-core-uefi-18.0rc1-bookworm-amd64.iso

(or similar).

Assuming all goes well, these builds will be the default (probably only) builds for v19.x+