feat: image cache gen

[frezbo]

Fixes: #9611

[frezbo]

❯ _out/talosctl-linux-amd64 image cache-create --images ghcr.io/siderolabs/extensions:sha256-1ec1e7d0c561ae2466292e3308792c5ab9dc7e3c8fea3025744c4537be6a2f69.sig --images ghcr.io/siderolabs/extensions:v1.8.3 --cache-path /tmp/cache.tar

❯ crane push /tmp/cache.tar 127.0.0.1:5010/frezbo/cache:latest
2024/11/15 19:58:10 existing blob: sha256:a348e59f06de8f5212048da8615a70e3ee9bd1f075c3896e3ad1db7659440615
2024/11/15 19:58:10 pushed blob: sha256:fa6ca17b2c3e49fa512f43313f09b8ba5adfa238ad853ea794601db4dd8a99f9
2024/11/15 19:58:10 127.0.0.1:5010/frezbo/cache:latest: digest: sha256:036d51c6f7e4190debfd7d2bc3bf20566689dbb6c486df89c4a6a0ed408e9275 size: 425
127.0.0.1:5010/frezbo/cache@sha256:036d51c6f7e4190debfd7d2bc3bf20566689dbb6c486df89c4a6a0ed408e9275

❯ crane export 127.0.0.1:5010/frezbo/cache:latest - | tar tf -
tar: Removing leading `/' from member names
/blob/sha256:bd2fb5c432256b78a3b635fe6101fc07cd03468a6500a194279bf22122a4e8aa
/blob/sha256:d1e1a3f48a04df2cd2351d92a00777641ff422eec753ae3db1ba6bd6f80da164
/blob/sha256:e36ac478125ae264890cc4ac584e893957f00c242b21d2606c2b735b8ddbd132
/manifests/ghcr.io/siderolabs/extensions/digest/sha256:1ec1e7d0c561ae2466292e3308792c5ab9dc7e3c8fea3025744c4537be6a2f69
/manifests/ghcr.io/siderolabs/extensions/digest/sha256:64972d0a5e2f41ba37212e10392f6ebc8a6422b3db3ae0f6cd7cefffb3541515
/manifests/ghcr.io/siderolabs/extensions/reference/sha256-1ec1e7d0c561ae2466292e3308792c5ab9dc7e3c8fea3025744c4537be6a2f69.sig
/manifests/ghcr.io/siderolabs/extensions/reference/v1.8.3

[smira]

❯ crane export 127.0.0.1:5010/frezbo/cache:latest - | tar tf -
tar: Removing leading `/' from member names
/blob/sha256:bd2fb5c432256b78a3b635fe6101fc07cd03468a6500a194279bf22122a4e8aa
/manifests/ghcr.io/siderolabs/extensions/reference/v1.8.3

I guess we should drop the leading /

[frezbo]

/m