Proposal(feat): support multipart/byteranges

[byene0923]

Is your feature request related to a problem? Please describe. I see hertz only support Single part ranges, i think it's better to support Multipart ranges

Describe the solution you'd like

Describe alternatives you've considered

Additional context golang std http support it https://github.com/golang/go/blob/be0b2a393a5a7297a3c8f42ca7d5ad3e4b15dcbe/src/net/http/fs.go#L870

[byene0923]

After reading how hertz handle single part , i found it's quite different from go std http。 the core difference is go std http read the bytes once but hertz read the bytes may in serval times。 because hertz use copyZeroAlloc，this will make support Multipart ranges complicated i think how hertz support multipart/byteranges needs reviewing， i‘m writing the detail now。