fix(runtime-dom): cache event handlers by key/modifiers (fix #9849)

[LinusBorg]

Problem

When an event handler is used multiple times in a template, for events with different key modifiers, the first wrapped handler that gets created first is being cached and re-used as the handler for all further uses, which breaks the other listeners.

Solution

Cache the created wrapped handler functions in a map object keyed by the specific modifier(s) they were created for

fix #9849

Alternative PR: #9850. That PR's author opted to remove the caching altogether which I think is not what we want. Also the problem needs to be fixed for both withKeys() and withModifiers(), which my PR does.

[github-actions]

Size Report

Bundles

File	Size	Gzip	Brotli
runtime-dom.global.prod.js	87.1 kB (+94 B)	33.1 kB (+17 B)	29.9 kB (+37 B)
vue.global.prod.js	133 kB (+94 B)	50 kB (+21 B)	44.8 kB (+60 B)

Usages

Name	Size	Gzip	Brotli
createApp	48.4 kB	19 kB	17.4 kB
createSSRApp	51.6 kB	20.3 kB	18.5 kB
defineCustomElement	50.7 kB	19.8 kB	18.1 kB
overall	61.7 kB	23.9 kB	21.7 kB

[LinusBorg]

@RicardoErii Sorry for opening this after you sent #9850. I started my PR a couple hours ago and only submitted it now, before I checked for other PRs arriving meanwhile.