Improve parse errors

[taimoorzaeem]

Parse errors are not super helpful and could be improved.

ghci> import Data.Aeson.JSONPath
ghci> import Data.Aeson.QQ.Simple (aesonQQ)
ghci> json = [aesonQQ| { "key": "value" } |]

ghci> query "$. key" json
Left "failed to parse query: $. key" (line 1, column 3):
unexpected " "
expecting letter or "*"

ghci> query "$.$key" json
Left "failed to parse query: $.$key" (line 1, column 3):
unexpected "$"
expecting letter or "*"