refactor: eliminate eslint errors (#920)

* refactor: eliminate eslint errors as many as I can

* refactor: fix more eslint errors in the record module

* LINT: fix @typescript-eslint/unbound-method

* LINT: fix all eslint errors in source code

* LINT: fix as many eslint warnings as possible

Co-authored-by: Justin Halsall <Juice10@users.noreply.github.com>

packages/rrweb/tsconfig.json

@@ -11,7 +11,8 @@
     "outDir": "build",
     "lib": ["es6", "dom"],
     "downlevelIteration": true,
-    "importsNotUsedAsValues": "error"
+    "importsNotUsedAsValues": "error",
+    "strictBindCallApply": true
   },
   "exclude": ["test"],
   "include": [