Support Envoy HTTP Decompressor filter

[relu]

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It is a good optimization for situations where it is desired to decrease the size of the body of HTTP requests for performance or cost reasons (reducing bandwidth usage).

The ability to decompress compressed HTTP body payloads is already a supported feature of Envoy via the decompressor filter.

Contour already supports the compressor filter for responses, which it has enabled by default with hardcoded configuration. Something similar can probably be done with the decompressor filter, however, it could be desirable to allow users to have more control over the configuration settings e.g. tweak compression algorithm-specific settings, enabling/disabling different compression algorithms, enabling or tuning the filter only for requests or responses.

Related to https://github.com/projectcontour/contour/discussions/5325.