Add support for the legacy_boot flag on GPT to manual partitioning

On GPT, the "boot" flag actually means "esp", so make the "Bootable" setting control the "legacy_boot" flag instead. This flag is needed by some arm64 platorms.

partman-base!11 (merged) is also required for full support.

Closes: #1034814

mentioned in merge request partman-base!11 (merged)

changed the description

added 1 commit

• ea24c119 - choose_method/biosgrub: Do not create the 'bootable' file

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I couldn't see any issues in tests, so I think it is ok to merge this, together with partman-base!11 (merged).

merged

mentioned in commit a3a8ac1b