Change emit target to ES2022

[jrieken]

Looks like we have broad support for ES2022 features. Static initialisers are the slight exception as they are only in Safari since ~2months. We might want to special case them, but otherwise we should be good to go: https://caniuse.com/sr_es13.

[jrieken]

On native privates: using them will be faster than weak-map-privates but slower than normal properties (much, much slower for Safari): https://jsbench.me/0gljcn4wzt/2

[jrieken]

Some, perf number for some new API

• native privates - https://jsbench.me/0gljcn4wzt/2, faster than WeakMap privates but slower than conventional privates
• Array.at - https://jsbench.me/vhljct96ph/1 slower than []-access
• ES2022 class definitions - likely faster because of less prototype changes needs useDefineForClassFields which need broader adoption because of semantic change. Use useDefineForClassFields compiler options #186726

[jrieken]

Upstream issues for private property performance

• v8 -> https://bugs.chromium.org/p/v8/issues/detail?id=14127
• Webkit -> https://bugs.webkit.org/show_bug.cgi?id=258660