clr-boot-manager doesn't handle EFI partition out of space

[bwarden]

clr-boot-manager is super cautious about writing to the VFAT filesystem of the EFI partition to reduce the risk of unbootable states (in case of power failure, for example). When updating content, even for a duplicate file, CBM will create a duplicate file and then rename it to the destination file. As a result, if there is insufficient free space in the EFI partition to hold the duplicate content temporarily, CBM will fail to complete the update, and will require manual cleanup of the partition in order to recover.

We should add some heuristics for identifying files that can be deleted or not duplicated if we run out of space, along with safe cleanup in case of failures, so we don't leave files behind.

Related to #3192.