Add cilium CNI support to cluster models

[ormequ]

Changes:

• Added CNI enums and settings to cluster schemas
• Split cluster response view models due to api difference: ListView for list responses, GetView for get/create/update/upgrade responses. cni_cilium_settings is present only in GetView

BREAKING CHANGES:

• Public type cluster.View is replaced by cluster.GetView / cluster.ListView.
• Method return types in pkg/v1/cluster changed accordingly.

[TawR1024]

@ormequ, according to breaking changes in this PR, I recommend you to change module version to v2.

@pavelpereyma @kolsean Any objections?

[ormequ]

We personally discussed and decided to change only tag version to v1