chore(build): Upgrade to Prettier 2.x

[lobsterkatie]

This upgrades all of our packages to use the latest version of Prettier, which is currently 2.5.1, in order to have support for linting of code written in typescript 3.8 and above.

When Prettier went to 2.0, it introduced some changes to its defaults, most notably:

• casting between two unlike types, with a cast to unknown in between, no longer requires parentheses around the first cast,
• inline functions defined with the function keyword now have a space after the word function, and
• indentation of multi-line expressions and statements is adjusted, sometimes to make more lines, sometimes fewer.

All three of these have been applied to all of the code in the repo.

The final change to defaults - to make it so that parameter lists in arrow functions always have parentheses around them, even if they only consist of one parameter - led to a lot of visual noise, so it's been overridden to preserve the current formatting.

[github-actions]

size-limit report

Path	Base Size (3f3c75b)	Current Size	Change
@sentry/browser - CDN Bundle (gzipped)	19.68 KB	19.69 KB	+0.01% 🔺
@sentry/browser - CDN Bundle (minified)	62.85 KB	62.86 KB	+0.01% 🔺
@sentry/browser - Webpack	22.2 KB	22.2 KB	0%
@sentry/browser - Webpack - gzip = false	75.99 KB	75.99 KB	0%
@sentry/react - Webpack	22.24 KB	22.24 KB	0%
@sentry/nextjs Client - Webpack	46.22 KB	46.22 KB	0%
@sentry/browser + @sentry/tracing - CDN Bundle (gzipped)	28.21 KB	28.22 KB	+0.01% 🔺

[AbhiPrasad]

rip rebasing off master