Feature request: Hover for variables and attributes

[wingyplus]

Environment

• Elixir & Erlang versions (elixir --version): 1.12.1
• Operating system: Windows 10 64-bit
• Editor or IDE name (e.g. Emacs/VSCode): VSCode
• Editor Plugin/LSP Client name:

Description

Consider the example code below:

defmodule Vector do
  @spec magnitude(Vec2.t()) :: number()
  def magnitude(%Vec2{} = v), do: :math.sqrt(:math.pow(v.x, 2) + :math.pow(v.y, 2))

  @spec normalize(Vec2.t()) :: Vec2.t()
  def normalize(%Vec2{} = v) do
    length = magnitude(v)
    %{v | x: v.x / length, y: v.y / length}
  end
end

When I hover mouse on length in function normalize, the hover document will show length built-in document. But since magnitude function has type spec. I expected the hover should show it as a number or not show when hover on length variable.

[lukaszsamson]

Depends on #170

[lukaszsamson]

Partially addressed in #233

[lukaszsamson]

Docs provider now handles variables, attributes and reserved words. I'm going to extract the part about type inference to a separate issue