New config-file first configuration approach

[mclasmeier]

Summary

• Introduces deployer.Config (internal/deployer/config.go) — a single, self-contained, YAML-serializable configuration struct that replaces ~20 loose variables, setter methods, and override maps scattered across the deployer and CLI layers.
• Replaces ad-hoc --override / --set machinery with a config-file-first model: --config/-c loads a full YAML config, --set writes directly into the Config struct via dotted paths, and all CLI flags are now configShortCut wrappers that mutate the same struct.
• Extracts first-class types into internal/types/ — ClusterType, Exposure, and ResourceProfile are now typed enums with YAML marshal/unmarshal, replacing free-form strings.
• Simplifies clusterdefaults — collapses the Manager/Detector/Applicator abstraction (flagged as over-engineered via TODO(ROX-34499)) into a single ApplyClusterDefaults function that merges a defaults map into Config.
• Adds --dry-run flag and moves config resolution (version lookup, operator config, spec composition) into runDeploy before the deployer is invoked.
• Slims down Deployer — removes ~15 fields and ~10 setter methods (SetMainImageTag, SetFeatureFlags, SetUseOLM, SetPortForwardingEnabled, etc.). The deployer now receives configuration via SetConfig() and reads everything from d.config.*.

This PR takes care of

• Proposal: Consolidate roxie deployment config in a single "config" file #113
• Support configurable namespaces #103

and addresses a couple of other TODOs in the code.

[mclasmeier]

@porridge @AlexVulaj merged in current main.

[mclasmeier]

@porridge I believe I have now addressed all of your comments except the one about helper functions for the pflag setup.

[mclasmeier]

@porridge, @AlexVulaj I have reworked the flag parsing setup, reducing duplication and complexity.

[mclasmeier]

(Manually) merged in main branch to fix conflicts.