feat: set custom userAgent

[fuhlig]

Motivation:

• emulate userAgent if page parses UA
• not polute analytics data by using custom userAgent that can be excluded from analytics
• Playwright does not allow setting userAgent in onReady script via page.setUserAgent() like puppeteer does and needs to be set in browser context https://github.com/microsoft/playwright/issues/697

Features:

• set userAgent via scenario.userAgent or config.userAgent
• for both Puppeteer & Playwright

Testing:

npm run ua-test -- --engine="puppeteer" --browser="chromium"
npm run ua-test -- --engine="puppeteer" --browser="firefox"

npm run ua-test -- --engine="playwright" --browser="chromium"
npm run ua-test -- --engine="playwright" --browser="firefox"
npm run ua-test -- --engine="playwright" --browser="webkit"

Examples

Playwright

Puppeteer