Add zstd content-encoding

[vuolter]

Describe the feature

It would be great to have support for zstd compression (https://github.com/facebook/zstd).
Browsers are now quite compatible with this content encoding (https://caniuse.com/zstd).
Thank you

Additional information

• Would you be willing to help implement this feature?
• Could this feature be implemented as a module?

Final checks

• Check existing discussions and issues.