perfetto: add Zstd as a trace compression codec (#6459)

The tracing service could already compress its output with deflate. This
adds Zstd, which produces smaller traces at a similar speed.

- Traces opt in with the new TraceConfig.compression field: set
  compression.zstd for Zstd or compression.deflate for deflate. If both
  are set, the higher field number wins (so zstd over deflate).
- Zstd's level is configurable via compression.zstd.level (1 fastest to
22
  smallest; 0 or unset uses zstd's default).
- The old compression_type field is now deprecated but still honored, so
  services that predate `compression` keep compressing.
- The service picks the codec from the config and runs it directly. A
  codec's library is only linked when its build flag (PERFETTO_ZLIB /
PERFETTO_ZSTD) is on, so libz/libzstd stay out of builds that don't use
  compression, such as the SDK.
- Each codec is configured by its own proto message, so the service
never
  needs to know a codec's specific options.
- Adding a codec later (e.g. lz4) is a new compressor file, one branch
in
  the service, and a proto sub-message - nothing else changes.

Bug: 529304320