Set the ESP flag in partition rather than bootloader.

The manual partitioning setup was already requiring the user to check
the ESP flag for the EFI System Partition. Now the autopartitioning also
sets it directly (a one-line change). The sgdisk call in the bootloader
module is thus no longer necessary (it was only a workaround because
kpmcore < 2.1.0 did not support FlagEsp), so remove that snippet.

This fixes configurations such as NVME disks where splitting boot_device
into boot_device[-1:] and boot_device[:-1] is not the correct split
(because the partition gets a 2-letter suffix) (reported by demmm on
IRC).

src/modules/partition/core/PartitionActions.cpp

@@ -140,7 +140,8 @@ doAutopartition( PartitionCoreModule* core, Device* dev, const QString& luksPass
             PartitionRole( PartitionRole::Primary ),
             FileSystem::Fat32,
             firstFreeSector,
-            lastSector
+            lastSector,
+            PartitionTable::FlagEsp
         );
         PartitionInfo::setFormat( efiPartition, true );
         PartitionInfo::setMountPoint( efiPartition, Calamares::JobQueue::instance()