Move primitives and runtime out of src/common/

Relocate src/common/primitives and src/common/runtime to src/primitives
and src/runtime. Add src/tsconfig.json as the primitives+runtime solution.
Update tsconfigs, esbuild, webpack aliases, publish path, and docs.

Co-authored-by: Daniel Imms <Tyriar@users.noreply.github.com>

src/primitives/Platform.ts

@@ -0,0 +1,54 @@
+/**
+ * Copyright (c) 2016 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+interface INavigator {
+  userAgent: string;
+  language: string;
+  platform: string;
+}
+
+// We're declaring a navigator global here as we expect it in all runtimes (node and browser), but
+// we want this module to live in common.
+declare const navigator: INavigator;
+declare const process: unknown;
+
+// navigator.userAgent is also checked here because bundling with the process module can cause
+// issues otherwise. Note that navigator exists in Node.js 21+ but the userAgent is
+// "Node.js/<version>".
+export const isNode = (typeof process !== 'undefined' && 'title' in (process as any) && (typeof navigator === 'undefined' || navigator.userAgent.startsWith('Node.js/'))) ? true : false;
+const userAgent = (isNode) ? 'node' : navigator.userAgent;
+const platform = (isNode) ? 'node' : navigator.platform;
+
+export const isFirefox = userAgent.includes('Firefox');
+export const isChrome = userAgent.includes('Chrome');
+export const isLegacyEdge = userAgent.includes('Edge');
+export const isSafari = /^((?!chrome|android).)*safari/i.test(userAgent);
+
+interface IZoomWindow {
+  devicePixelRatio?: number;
+}
+
+export function getZoomFactor(_targetWindow: IZoomWindow): number {
+  return 1;
+}
+export function getSafariVersion(): number {
+  if (!isSafari) {
+    return 0;
+  }
+  const majorVersion = userAgent.match(/Version\/(\d+)/);
+  if (majorVersion === null || majorVersion.length < 2) {
+    return 0;
+  }
+  return parseInt(majorVersion[1]);
+}
+
+// Find the users platform. We use this to interpret the meta key
+// and ISO third level shifts.
+// http://stackoverflow.com/q/19877924/577598
+export const isMac = ['Macintosh', 'MacIntel', 'MacPPC', 'Mac68K'].includes(platform);
+export const isWindows = ['Windows', 'Win16', 'Win32', 'WinCE'].includes(platform);
+export const isLinux = platform.indexOf('Linux') >= 0;
+// Note that when this is true, isLinux will also be true.
+export const isChromeOS = /\bCrOS\b/.test(userAgent);