Enhance Page to take a PageDetails upon construction.

With #private variables, we need to move away from having code in the base
class that can use overrides in the subclasses.  Instead, we will need to pass
them in through the constructor or other mechanisms.  Here, we are adding some
items similar to what we already use, but can do differently.

Issue #130.

␄

linkedin-tool.user.js

@@ -1751,6 +1751,8 @@
      */
     _pathname;
 
+    #pageReadyCSS
+
     /**
      * @type {string} - CSS selector for capturing clicks on this page.  If
      * overridden, then the class should also provide a _onClick() method.
@@ -1788,12 +1790,34 @@
       condition: '!inputFocus && !inDialog',
     };
 
-    /** Create a Page instance. */
-    constructor() {
+    /**
+     * @typedef {object} PageDetails
+     * @property {string|RegExp} [pathname=RegExp] - Pathname portion of the
+     * URL this page should handle.
+     * @property {string} [pageReadyCSS='body'] - CSS selector that is used to
+     * detect that the page is loaded enough to activate.
+     */
+
+    /**
+     * Create a Page instance.
+     * @param {PageDetails} details - Details about the instance.
+     */
+    constructor(details = {}) {
       if (new.target === Page) {
         throw new TypeError('Abstract class; do not instantiate directly.');
       }
+      if (details.pathname) {
+        if (details.pathname instanceof RegExp) {
+          this.#pathnameRE = details.pathname;
+        } else {
+          this.#pathnameRE = RegExp(`^${details.pathname}$`, 'u');
+        }
+      }
+      ({
+        pageReadyCSS: this.#pageReadyCSS = 'body',
+      } = details);
       this.#logger = new Logger(this.constructor.name);
+      this.#logger.log('Base page constructed', this);
     }
 
     /**