Add delimiter meta to demote calls with quoted identifier

[jonatanklosko]

Currently, the AST does not distinguish between Foo.foo and Foo."foo". This adds :delimiter meta to the call root (where the identifier location is also stored), so similarly to atoms:

iex(1)> Code.string_to_quoted!(~S[:"🐈"],
...(1)>   token_metadata: true,
...(1)>   literal_encoder: &{:ok, {:__block__, &2, [&1]}}
...(1)> )
{:__block__, [delimiter: "\"", line: 1], [:"🐈"]}
iex(2)> Code.string_to_quoted!(~S[Foo."🐈"],
...(2)>   token_metadata: true,
...(2)>   literal_encoder: &{:ok, {:__block__, &2, [&1]}}
...(2)> )
{{:., [line: 1], [{:__aliases__, [last: [line: 1], line: 1], [:Foo]}, :"🐈"]},
 [no_parens: true, delimiter: "\"", line: 1], []}

[josevalim]

💚 💙 💜 💛 ❤️