feat(node): add warning of future node support (#3271)

this commit adds a warning to the console stating that support for node
v14.5.0 and under will be removed in a future major version update of
stencil. this commit only adds the notice to the `bin` entrypoint of
stencil, and does not add any notice to using compiler api's directly
(we expect the latter to be handled by `package.json#engines`).

bin/stencil

@@ -2,6 +2,7 @@
 'use strict';
 
 var minimumVersion = '12.10';
+var futureDeprecationMinVersion = '14.0';
 var recommendedVersion = '14.5';
 var currentVersion = process.versions.node;
 
@@ -22,7 +23,13 @@ if (isNodeLT(minimumVersion)) {
   process.exit(1);
 }
 
-if (isNodeLT(recommendedVersion)) {
+if (isNodeLT(futureDeprecationMinVersion)) {
+  console.warn(
+    '\nIn an upcoming major release of Stencil, Node v' +
+    recommendedVersion +
+    '.0 or higher will be required.\n'
+  );
+} else if (isNodeLT(recommendedVersion)) {
   console.warn(
     '\nYour current version of Node is v' +
       currentVersion +