Stop using Babel; compile JS to ES2020 (#4066)

Co-authored-by: wch <[email protected]>
Co-authored-by: Garrick Aden-Buie <[email protected]>
Co-authored-by: gadenbuie <[email protected]>
Co-authored-by: Barret Schloerke <[email protected]>

Author: 3 people

.Rbuildignore

@@ -26,7 +26,6 @@
 ^\.vscode$
 ^\.madgerc$
 ^\.prettierrc\.yml$
-^babel\.config\.json$
 ^jest\.config\.js$
 ^package\.json$
 ^tsconfig\.json$

NEWS.md

@@ -9,6 +9,8 @@
 
 * Shiny now uses `{cli}` instead of `{crayon}` for rich log messages. (@olivroy #4170)
 
+* Shiny's Typescript assets are now compiled to ES2021 instead of ES5. (#4066)
+
 ## Bug fixes
 
 * Fixed a bug with modals where calling `removeModal()` too quickly after `showModal()` would fail to remove the modal if the remove modal message was received while the modal was in the process of being revealed. (#4173)