chore: adjust top-level config do ignore third-party/projects/

Stuff under third-party/projects/ is stuff that we don't plan on
touching much at all -- just minimal forks up third-party code with
small patches on top -- so we don't want to churn it all up just to make
it match our formatting and linting rules.

Author: wincent

.eslintignore

@@ -26,4 +26,5 @@
 # Third-party code
 #
 
+/third-party/projects
 node_modules

.prettierignore

@@ -24,3 +24,9 @@
 /copyright.js
 /maintenance/projects/**/copyright.js
 /projects/**/copyright.js
+
+#
+# Third-party.
+#
+
+/third-party/projects

jest.config.js

@@ -40,6 +40,10 @@ module.exports = {
 		'<rootDir>/projects/js-toolkit',
 		'<rootDir>/projects/npm-tools/packages/npm-scripts',
 
+		// Third-party.
+
+		'<rootDir>/third-party/projects',
+
 		// Standard ignores.
 
 		'/node_modules/',