qemu_migration_params: Refactor qemuMigrationParamsApply
qemu_migration_params: Refactor qemuMigrationParamsApply

qemuMigrationParamsApply restricts when capabilities can be set, but
this is not useful in all cases. Let's create new helpers for setting
migration capabilities and parameters which can be reused in more places
without the restriction.

https://bugzilla.redhat.com/show_bug.cgi?id=2107892

Signed-off-by: Jiri Denemark <62bdf77dc47919a4d59a91822129d14633cfca81@redhat.com>
Reviewed-by: Michal Privoznik <83d82aaba2eed257f4814b0c239c260c4caaadf0@redhat.com>

libvirt/libvirt,libvirt/libvirt,crobinso/libvirt,zippy2/libvirt,olafhering/libvirt,jfehlig/libvirt,jfehlig/libvirt,olafhering/libvirt,olafhering/libvirt,zippy2/libvirt,zippy2/libvirt,jfehlig/libvirt,crobinso/libvirt,jfehlig/libvirt,libvirt/libvirt,olafhering/libvirt,zippy2/libvirt,libvirt/libvirt,crobinso/libvirt,crobinso/libvirt