Dot option support for nested struct

[rkdgusxo66]

Hello
this library has been very helpful in our project.

Currently, nested structs are encoded using bracket notation
However, some APIs require dot-notation keys insted, such as

user.from=1601623397728
user.verified=true

Proposed Feature

Introduce an optional tag modifier "dot":

type Query struct {
    User User `qs:"user,dot"`
}

Expected output:
user.from=1601623397728&user.verified=true

Thank you for considering this feature.

[sonh]

Hello @rkdgusxo66
It's feasible, however I'm not available to begin with this immediately. I'll add this feature in the next few days