Add ZSTD compression support to forward plugin

[zamazan4ik]

Is your feature request related to a problem? Please describe.

ZSTD is a modern compression algorithm developed by Facebook. Using ZSTD has one of the best compression/resource consumption ratios in the compression area.

Describe the solution you'd like

Have a ZSTD compression support in additoin to GZip. Would be awesome, if will be a possibility to specify the compression level as well.

Describe alternatives you've considered

Left all things as is.

Additional context

Maybe this change will require changing FluentBit implementation as well.