feat(instance): add scratch storage

[scaleway-bot]

No description provided.

[codecov-commenter]

Codecov Report

Merging #3346 (329f28a) into master (4bd94c9) will increase coverage by 0.04%.
Report is 10 commits behind head on master.
The diff coverage is 71.06%.

@@            Coverage Diff             @@
##           master    #3346      +/-   ##
==========================================
+ Coverage   75.65%   75.70%   +0.04%     
==========================================
  Files         172      175       +3     
  Lines       38198    39031     +833     
==========================================
+ Hits        28898    29547     +649     
- Misses       8258     8413     +155     
- Partials     1042     1071      +29     

Files Changed	Coverage Δ
internal/namespaces/k8s/v1/custom_cluster.go	79.57% <0.00%> (ø)
...ternal/namespaces/vpc/v2/custom_private_network.go	69.93% <69.93%> (ø)
...espaces/container/v1beta1/custom_deploy_helpers.go	71.87% <100.00%> (ø)
...ternal/namespaces/function/v1beta1/function_cli.go	80.61% <100.00%> (+0.01%)	⬆️
internal/namespaces/instance/v1/instance_cli.go	87.93% <100.00%> (ø)
internal/namespaces/rdb/v1/custom_user.go	81.13% <100.00%> (+0.36%)	⬆️
internal/namespaces/vpc/v2/custom.go	100.00% <100.00%> (ø)

... and 2 files with indirect coverage changes