Firebird services support

[artyom-smirnov]

Low level services wire protocol implementation and wrappers for backup, nbackup, user and trace management

[artyom-smirnov]

This is WIP pull request. Before making it "ready to merge" I want to add maintenance management (repair, sweep, etc) and add some testing. If you have a some time, take a glance. May be you see it somehow different.

[bat22]

In my opinion:

• use int instead of int16 here

  type XPBReader struct {
  buf []byte
  pos int16
  }

• Bytes() is more idiomatic name for

  func (pb *XPBWriter) GetBuffer() []byte

• use append() instead of bytes.Join() in XPBWriter (with method Reset() object can be reused with existing buffer)

ps what does XPB mean?

[artyom-smirnov]

what does XPB mean?

Just common name for DPB, RPB.

[bat22]

I think most likely case for XPBReader.Reset is reset with new byte slice for example: https://pkg.go.dev/strings#Reader.Reset, https://pkg.go.dev/bytes#Reader.Reset

[nakagami]

Great work!

I don't know much about the service API, but I think the code is good. Test code is also good.

It would be even better if you could include an example in the README if possible, but I think I will merge it without the README when this work is completed.