Option to keep spaces before inline comments

Add a keepSpaces or keepSpacesBeforeLineComments similar too keepLines that preserves the spaces between values and inline comments at the end of the line.

This will help to avoid unnecessary changes when formatting tsconfig.json files:

Original:

    /* Language and Environment */
    "target": "es2016",                                  /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */
    // "lib": [],                                        /* Specify a set of bundled library declaration files that describe the target runtime environment. */

Formatted:

    /* Language and Environment */
    "target": "es2016", /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */
    // "lib": [],                                        /* Specify a set of bundled library declaration files that describe the target runtime environment. */

Diff:

     /* Language and Environment */
-    "target": "es2016",                                  /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */
+    "target": "es2016", /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */
     // "lib": [],                                        /* Specify a set of bundled library declaration files that describe the target runtime environment. */

Start by reading the existing keepLines option and the linked pull request, then trace the formatter API that handles inline comments. Use the tsconfig.json examples as the behavior reference: when the new option is enabled, spaces before end-of-line comments should be preserved without changing other formatting.