feat: principal backwards compatibility (#614)

* feat: backwards compatibility with PrincipalBase
* documentation
* PrincipalLike and adding isPrincipal utility methods
* upgrading node version

Co-authored-by: Eric Swanson <64809312+ericswanson-dfinity@users.noreply.github.com>

.nvmrc

@@ -1 +1 @@
-16.10
+v16.17.0

docs/generated/changelog.html

@@ -10,6 +10,17 @@
     <h1>Agent-JS Changelog</h1>
 
     <section>
+      <h2>Version 1.0.0</h2>
+      <ul>
+        <li>Backwards compatibility with 0.9.3 for @dfinity/principal</li>
+        <ul>
+          <li>
+            If you have a TypeScript interface that uses a Principal, we recommend updating and
+            using the abstract class PrincipalLike as the signature. It will be compatible across
+            versions of agent-js.
+          </li>
+        </ul>
+      </ul>
       <h2>Version 0.13.2</h2>
       <ul>
         <li>auth-client avoids localstorage global and can be used in a web worker or nodejs</li>