install: Verify target supports fsverity early on

Failed to reboot to original system (xfs) after bootc install ghcr.io/bootc-dev/dev-bootc:stream10-uki

```
# podman run -ti --rm --privileged --pid=host --security-opt label=type:unconfined_t -v /var/lib/containers:/var/lib/containers -v /dev:/
dev -v /:/target ghcr.io/bootc-dev/dev-bootc:stream10-uki bootc install to-existing-root --composefs-backend --acknowledge-destructive
Installing image: docker://ghcr.io/bootc-dev/dev-bootc:stream10-uki
Digest: sha256:bc013b1612a470db61e6a9e45452286afd3741518f9cd3d7d43eaaa28528d7f1
Fetching config 73342bfa908c498ec230dda4eeb0a8b3af2cc29d093ceb4cfe43dedc64418ecf
...
...
...
Fetching layer d83d2c94c45599e8247985017bbcd4cd11254a6e23aadf30228f05c18c782042
error: Installing to filesystem: Unable to pull container image containers-storage:ghcr.io/bootc-dev/dev-bootc:stream10-uki: Failed to pull config Descriptor { media_type: ImageConfig, digest: Digest { algorithm: Sha256, value: "sha256:73342bfa908c498ec230dda4eeb0a8b3af2cc29d093ceb4cfe43dedc64418ecf", split: 6 }, size: 16283, urls: None, annotations: None, platform: None, artifact_type: None, data: None }: Enabling verity digest: Filesystem does not support fs-verity
# reboot
```
Console log after reboot
```
BdsDxe: failed to load Boot0002 "UEFI QEMU QEMU HARDDISK " from PciRoot(0x0)/Pci(0x4,0x0)/Scsi(0x0,0x0): Not Found

>>Start PXE over IPv4.
PXE-E16: No valid offer received.
BdsDxe: failed to load Boot0003 "UEFI PXEv4 (MAC:525400123456)" from PciRoot(0x0)/Pci(0x2,0x0)/MAC(525400123456,0x1)/IPv4(0.0.0.0,0x0,DHCP,0.0.0.0,0.0.0.0,0.0.0.0): Not Found

>>Start PXE over IPv6.
PXE-E16: No valid offer received.
BdsDxe: failed to load Boot0004 "UEFI PXEv6 (MAC:525400123456)" from PciRoot(0x0)/Pci(0x2,0x0)/MAC(525400123456,0x1)/IPv6(0000:0000:0000:0000:0000:0000:0000:0000,0x0,Static,0000:0000:0000:0000:0000:0000:0000:0000,0x40,0000:0000:0000:0000:0000:0000:0000:0000): Not Found
```