Implement Mixed Mode State Detection

[heypnus]

Replace the global boolean cf.CoeConfig.EnableVPCNetwork with namespace-label-driven mixed-mode state: HasT1Namespaces and HasVPCNamespaces.

New module: pkg/config/mixed_mode.go

• Checks SupervisorCapabilities CRD (iaas.vmware.com/v1alpha1) for supports_per_namespace_network_providers capability.
• If supported: scans namespace labels (iaas.vmware.com/network-provider) to derive HasT1Namespaces (nsx-t1) and HasVPCNamespaces (nsx-vpc or vsphere-network).
• If not supported (legacy/pre-9.2): falls back to EnableVPCNetwork config flag.
• Provides InitializeMixedModeState(), RefreshMixedModeState(), HasT1Namespaces(), HasVPCNamespaces(), GetNamespaceNetworkProvider() APIs.

This enables NSX Operator to run in mixed mode where both T1 and VPC namespaces coexist, as required for VDS->VPC and T1->VPC migration.

Testing done: WIP

[codecov-commenter]

Codecov Report

❌ Patch coverage is 16.91176% with 113 lines in your changes missing coverage. Please review.
✅ Project coverage is 76.39%. Comparing base (c3a71ec) to head (f9ed8a5).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/config/mixed_mode.go	11.71%	98 Missing ⚠️
cmd/main.go	0.00%	14 Missing ⚠️
pkg/nsx/client.go	0.00%	0 Missing and 1 partial ⚠️

❌ Your patch status has failed because the patch coverage (16.91%) is below the target coverage (70.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1396      +/-   ##
==========================================
- Coverage   76.75%   76.39%   -0.37%     
==========================================
  Files         151      152       +1     
  Lines       21308    21436     +128     
==========================================
+ Hits        16356    16376      +20     
- Misses       3783     3892     +109     
+ Partials     1169     1168       -1     

Flag	Coverage Δ
unit-tests	76.39% <16.91%> (-0.37%)	⬇️

Files with missing lines	Coverage Δ
pkg/nsx/services/securitypolicy/parse.go	95.91% <100.00%> (ø)
pkg/nsx/util/license.go	100.00% <100.00%> (ø)
pkg/nsx/client.go	94.39% <0.00%> (-0.52%)	⬇️
cmd/main.go	0.00% <0.00%> (ø)
pkg/config/mixed_mode.go	11.71% <11.71%> (ø)

... and 1 file with indirect coverage changes

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