Config validate

[AleksandarSavchev]

How to categorize this PR?

/kind enhancement

What this PR does / why we need it:

Adds a diki config validate command that validated the structure and content of a diki configuration file. This is useful for catching configuration errors early (e.g. in CI) before attempting a full diki run.

The command validates:

• Provider IDs are known/registered
• No duplicate provider IDs
• Provider args parse correctly and required fields are present
• Ruleset IDs+Versions are supported for each provider
• No duplicate ruleset ID+Version combinations
• Per-rule option type/field validation
• Required ruleset args (e.g. shootName, projectNamespace for the garden provider)

Usage:

diki config validate config.yaml

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:

Release note:

Added `diki config validate` command for structural and content validation of configuration files

[gardener-prow]

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