feat(metrics): add flag to enable WASM metrics

[nojnhuh]

Description:
This change adds a command line flag to osm-controller and a Helm chart
parameter to enable the WASM stats Envoy extension.

---

This PR is part of several which together extend Envoy to generate custom
metrics needed to implement the SMI metrics spec (#984).
Here is a map of the PRs as they're currently planned:

1. (ref(injector): pass pod object to getEnvoySidecarContainerSpec #2479) ref(injector): pass pod object to getEnvoySidecarContainerSpec
2. (feat(metrics): add WASM metrics source #2488) feat(metrics): add WASM metrics source
3. (docs(metrics): Add docs for WASM stats #2503) docs(metrics): Add docs for WASM stats
4. (feat(metrics): Add WASM feature flag #2517) feat(metrics): Add WASM feature flag
5. (feat(metrics): Add stats.wasm to proxy config #2546) feat(metrics): Add stats.wasm to proxy config
6. (feat(injector): Add name, workload name, workload kind to PodMetadata #2554) feat(injector): Add name, workload name, workload kind to PodMetadata
7. (feat(metrics): Add source labels to WASM metrics #2571) feat(metrics): Add source labels to WASM metrics
8. (feat(metrics): Add dest labels to WASM metrics #2574) feat(metrics): Add dest labels to WASM metrics
9. (feat(metrics): Add "unknown" for dest labels on local replies #2587) feat(metrics): Add "unknown" for dest labels on local replies
10. (feat(metrics): clean up WASM metrics in Prometheus config #2603) feat(metrics): clean up WASM metrics in Prometheus config
11. (YOU ARE HERE) feat(metrics): add flag to enable WASM metrics
12. tests(e2e): add WASM metrics test

The remaining changes can be found here: main...nojnhuh:wasm-metrics

Affected area:

• New Functionality [ ]
• Documentation [ ]
• Install [ ]
• Control Plane [X]
• CLI Tool [ ]
• Certificate Management [ ]
• Networking [ ]
• Metrics [X]
• SMI Policy [ ]
• Security [ ]
• Tests [ ]
• CI System [ ]
• Performance [ ]
• Other [ ]

Please answer the following questions with yes/no.

• Does this change contain code from or inspired by another project? If so, did you notify the maintainers and provide attribution?
  No