fix(remix): Use import() to get react-router-dom in Express wrapper.

[onurtemizkan]

Details copied from: #5796 which is reverted by #5802

loadModule utility which we use to acquire react-router-dom can return null when called from Express wrapper.

I suspect the main reason is that we are not monkey-patching Remix core here, like we are doing in the base implementation, the package acquisition is not guaranteed to run when (or where?) react-router-dom is available.

Tried using dynamic imports, and it worked well on https://github.com/getsentry/vanguard

Parameterized Route Transaction

Root Transaction

Redirected Route Transaction

[AbhiPrasad]

Will is break if folks are bundling stuff (like in a serverless function)?

Can we just call import directly on react-router-dom?

[onurtemizkan]

Will is break if folks are bundling stuff (like in a serverless function)?

I think it depends on the packager used, but it seems there are some workarounds if such thing happens: https://www.serverless.com/plugins/serverless-jetpack#handling-dynamic-import-misses. It also applies to loadModule (using module.require) as far as I understand.

Can we just call import directly on react-router-dom?

Tried that and it's working, but while building @sentry/remix I got a warning from Rollup because, it actually tried to resolve the deps from sentry-javascript/node_modules on build time.