[v8] Add browser-runtime package

[mydea]

Lukas has identified a potential issue, if we want to bundle all dependencies of packages into a single index.js file, including all dependencies. If, as of now, e.g. @sentry/react depends on @sentry/browser and adds some more stuff on top it picks from @sentry/core, if @sentry/browser inlines @sentry/core it will not be possible to dedupe core imports in the react package.

A potential solution for this could be to have a @sentry-internal/browser-runtime package similar to the server-runtime package, which holds basically all the code from @sentry/browser, but does not bundle it all into one file. Then both @sentry/browser and the other browser packages like vue, react, ... can depend on browser-runtime too, and all of these can then bundle all their dependencies - including core - correctly into a single file.

This does not technically need to happen in v8, but is probably a requirement if we want to bundle all dependencies together.

[AbhiPrasad]

if we want to bundle all dependencies of packages into a single index.js file

I would avoid inlining deps if we can, having single index.js but keeping package boundaries between core/browser/nextjs etc. seems reasonable to me.

[lforst]

The plan is not to bundle dependencies but to just set preserveModules: false.

[mydea]

Hmm I don't remember anymore who brought this up, but I do remember this was mentioned at some point - but I have no strong feelings on this either way. If we don't want to inline core, then this is not necessary.

[Lms24]

In the interest of streamlining (going through #9508), let's table this for v8 - wdyt? I'll close the issue for now but we can reopen if necessary