Remove double colon in Hash keys (`:sym: "value"` → `sym: "value"`)

[amomchilov]

This PR depends on the changes in #1001. Only this last commit of this PR is unique to this change.

Description

• Both Chrome and VSCode automatically insert a : after the key, so the final result looks closer Ruby's Hash syntax, like: { sym: 1 }
• This is consistent with how both Chrome and VSCode render the keys of JavaScript objects

Here's an example for this hash:

h = {
  sym1: 1,
  sym2: 2,
  "str" => 3,
}

	Before	After
Chrome
VSCode

[st0012]

Are VS Code's pictures reversed?

[amomchilov]

@st0012 Yes they were. Fixed! 😅