[Feature Request] set pk column after columns creation

[kcmvp]

when create columns with CreateColumnsOf as below, there is no way to set a PK field.

` obj := map[string]any{
"name": "Roman",
"age": 35,
"wallet": 50.99,
"health": 100,
"mana": 200,
}

col := NewCollection()
col.CreateColumnsOf(obj)`

if there is a new API such as
collection.setPK(colName string)
then we can set an existing column as PK. Of course, this api only available when the collection is emtpy.

[kelindar]

I'm actually thinking of removing this API altogether, to keep overall API simple and more consistent. Maybe we can consider creating an "ORM" package for column that can auto-create column schemas off maps, structs etc. 🤔