Installer should detect small ESP in a dual boot

[Mario Limonciello]

If someone sets up Windows before Ubuntu, Windows will create an EFI system partition that gets reused by Ubuntu.

This is generally fine, but a major problem is that the EFI system partition is also where firmware updates are staged during a BIOS update.

If the ESP is too small, then the update won't be able to run. The command line fwupdmgr tool will show this type of message:

/boot/efi does not have sufficient space, required 93.2 MB, got 66.8 MB

This is a situation that should be handled at install time. If the ESP is too small to support updates later it should be resized or a new one created for Ubuntu to use.

[Mario Limonciello (superm1)]

And so it's clear how this size is determined by fwupd it's based on the size of the payload the system will be using (IE the SPI size):

https://github.com/fwupd/fwupd/blob/9713cead62e79da26d4c5637dd9682b21a9f0b21/plugins/uefi-capsule/fu-uefi-device.c#L635

The size is doubled because often the firmware updater will make a backup of the SPI to the ESP or will extract the payload while updating.

I think a reasonable default would be to ensure that there is 128MB of free space available to cover up to a 64Mb SPI part and a backup.