webui: add support for ISCSI storage for installation destination

[KKoukiou]

• Blocked on: webui: apis: dont repeat yourself anaconda#5281
• Needs more test coverage
• Needs reverse chap support in the UI (followup)
• Needs better presentation of the error messages - now presenting directly what we get from backend - (followup)
• Needs designer review - the current design is self inspired (followup) - @garrett is in sick leave
• Fix review comments from webui: add support for ISCSI storage for installation destination anaconda#5283

iscsi-storage-anaconda.mp4

• @vojtechtrefny I am trying to address your comment about added/removed disks with: storage: show toast notification when disks selection changed #32

[KKoukiou]

I am not planning to work on that in the near future. Keeping the branch alive for future resurection - but killing the PR.