Per discussion of #2513, Ubuntu Core was going to use UEFI removable
path as default esp path, and it needs to change some parts around
getting the esp path and searching the shim app path. Also, a new option
"FallbacktoRemovablePath" is added into uefi.conf to be applied in this
case, and it will be false by default.
Some system firmware helpfully 'deduplicate' the boot loader entries based on
the filepath, without taking into account either the label or optional data.
This means we have to use a custom copy of shim for firmware updates.
Some hardware from Lenovo deduplicates UEFI Boot entries, and uses the old
string 'Linux-Firmware-Updater' to avoid removing the firmware update entry.
Although this is forbidden in the UEFI specification we shouldn't break
firmware updates from old firmware versions.
Provide a quirk for this, and automatically whitelist anything with the LENOVO
SMBIOS Manufacturer.
