Add `defaultOptions` method to main beautifier

[bitwiseman]

Description

Related to #1364. #1568 added a basic implementation for this.

We need to add beautify.defaultOptions() that:

1. calls core Options constructor
2. calls each of the child defaultOptions()
3. removes the inherited settings and also the raw_options field

It should return something like what is shown below.

Finally, we should consider calling this method during the build to generate the .jsbeautifyrc file.

There should be one source of truth the settings for the project.

{
  "disabled": false,
  "eol": "auto",
  "end_with_newline": false,
  "indent_size": 4,
  "indent_char": " ",
  "indent_level": 0,
  "preserve_newlines": true,
  "max_preserve_newlines": 32786,
  "indent_with_tabs": false,
  "wrap_line_length": 0,
  "js": {
    "brace_preserve_inline": false,
    "brace_style": "collapse",
    "unindent_chained_methods": false,
    "break_chained_methods": false,
    "space_in_paren": false,
    "space_in_empty_paren": false,
    "jslint_happy": false,
    "space_after_anon_function": false,
    "space_after_named_function": false,
    "keep_array_indentation": false,
    "space_before_conditional": true,
    "unescape_strings": false,
    "e4x": false,
    "comma_first": false,
    "operator_position": "before-newline",
    "test_output_raw": false
  },
  "css": {
    "selector_separator_newline": true,
    "newline_between_rules": true,
    "space_around_combinator": false
  },
  "html": {
    "js": {},
    "css": {},
    "indent_inner_html": false,
    "indent_body_inner_html": true,
    "indent_head_inner_html": true,
    "indent_handlebars": true,
    "wrap_attributes": "auto",
    "wrap_attributes_indent_size": 4,
    "extra_liners": [
        "head",
        "body",
        "/html"
    ],
    "inline": [
      "a", "abbr", "area", "audio", "b", "bdi", "bdo", "br", "button", "canvas", "cite", "code", "data", "datalist", "del", "dfn", "em", "embed", "i", "iframe", "img", "input", "ins", "kbd", "keygen", "label", "map", "mark", "math", "meter", "noscript", "object", "output", "progress", "q", "ruby", "s", "samp", "select", "small", "span", "strong", "sub", "sup", "svg", "template", "textarea", "time", "u", "var", "video", "wbr", "text", "acronym", "address", "big", "dt", "ins", "strike", "tt"
    ],
    "void_elements": [
      "area", "base", "br", "col", "embed", "hr", "img", "input", "keygen", "link", "menuitem", "meta", "param", "source", "track", "wbr", "!doctype", "?xml", "?php", "?=", "basefont", "isindex"
    ],
    "unformatted": [],
    "content_unformatted": [
        "pre",
        "textarea"
    ],
    "indent_scripts": "normal"
  }
}

[Lakshmidurgagodasi]

I like to work on this can i get started

[Gitmuru]

will work on this