first class query encoder

[wibed]

this issue mentions the removal of the dependency to foundation: #299
idk how far this has gotten nor if it is still on the radar, but the dependency seems to still be there.

is it viable to include a first class query encoder. it seems every library that depends on ahc does include an encoder of some sorts.

[Lukasa]

I think it's viable to do so, even with a dropped Foundation dependency. There are non-Foundation-using Base64 encoders. Yes, I think such a thing is in scope with the right Base64 implementation. @fabianfett may have opinions on exactly which one.

[Lukasa]

Wait, I'm clearly losing my mind: we need percent-encoding, not base64. I think we can safely do that without Foundation as well.