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. */

まず既存の keepLines オプションとリンク先の pull request を読み、その後、インラインコメントを処理する formatter API をたどってください。動作のリファレンスとして tsconfig.json の例を使用してください。新しいオプションを有効にした場合、他のフォーマットを変更せずに、行末コメントの前のスペースを保持する必要があります。