More bugfixes

[FnControlOption]

Fix snippets of aliased functions

Closes #1327

Commit 53b40b3 from #1319 has broken snippet insertion for aliased functions.

Before that commit completion of std.ArrayHashMap results in std.ArrayHashMap(comptime K: type, comptime V: type, comptime Context: type, comptime store_hash: bool) after that commit it results in std.ArrayHashMap.

Show //! doc comments in hover and completions

Closes #304

In Something.zig:

//! top level comment

/// inner comment
a: i32

In main.zig:

const Something = @import("Something.zig");
pub fn main() void {
  const some = Something { .a = 2 }; // Something has no documentation
  some.a; // Has top level documentation and inner documentation 
}

(#308 removed the top level comment for members)

Make Go to Definition fully resolve const Foo = @import("Foo.zig")

Also fix broken Go to Declaration caused by Server API redesign in #1311

Closes #322

const std = @import("std");
const fs = std.fs;

Consider clicking on the .fs, this opens zig/lib/std/std.zig to a line that says const fs = @import("fs.zig");.

The request here is to make it so that when the definition being goto'd is an @import("file.zig");, open file.zig instead.