chore(kuma-cp) add route and virtual host configuration helpers

[jpeach]

Summary

Add configuration helper adaptors for envoy VirtualHost and
RouteConfiguration types.

Full changelog

N/A

Issues resolved

N/A

Documentation

N/A

Testing

• Unit tests
• E2E tests
• Manual testing on Universal
• Manual testing on Kubernetes

Backwards compatibility

• Add backport-to-stable label if the code is backwards compatible. Otherwise, list breaking changes.

[codecov-commenter]

Codecov Report

Merging #2517 (31b61ce) into master (2e3ace0) will increase coverage by 0.04%.
The diff coverage is 73.33%.

@@            Coverage Diff             @@
##           master    #2517      +/-   ##
==========================================
+ Coverage   52.18%   52.22%   +0.04%     
==========================================
  Files         865      865              
  Lines       48284    48295      +11     
==========================================
+ Hits        25196    25222      +26     
+ Misses      21047    21029      -18     
- Partials     2041     2044       +3     

Impacted Files	Coverage Δ
pkg/xds/envoy/routes/v3/configurer.go	25.00% <25.00%> (ø)
pkg/xds/envoy/routes/configurers.go	100.00% <100.00%> (ø)
...kg/xds/envoy/routes/route_configuration_builder.go	84.00% <100.00%> (+3.04%)	⬆️
pkg/xds/envoy/routes/virtual_host_builder.go	84.00% <100.00%> (+3.04%)	⬆️
pkg/xds/cache/once/cache.go	87.17% <0.00%> (-7.70%)	⬇️
pkg/core/resources/manager/cache.go	81.81% <0.00%> (ø)
api/observability/v1/mads.pb.go	35.56% <0.00%> (+1.03%)	⬆️
pkg/insights/resyncer.go	66.38% <0.00%> (+1.68%)	⬆️
pkg/mads/v1/client/client.go	43.75% <0.00%> (+2.50%)	⬆️
... and 4 more

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