feat(nextjs): Add ability for integration tests to use linked @sentry/xxxx packages

[lobsterkatie]

In the nextjs integration tests, we use file dependencies for all of the packages in the sentry-javascript repo, so that the tests test the local (rather than published) version of the SDK. We don't do the same for @sentry/cli or @sentry/webpack-plugin, though, because they're in a separate repo and we can't predict where the local copy of that repo lives. As a result, we currently can't (in the nextjs integration tests, at least) test any local changes in either package.

This solves that problem by optionally linking to the local copies of those repos as part of the integration test runner script. In order to use this optional linking:

• To link @sentry/cli, set LINKED_CLI_REPO=<abs path of local sentry-cli repo>.
• To link @sentry/webpack-plugin, set the CLI variable above (since @sentry/cli is a dependency of @sentry/webpack-plugin, we need to link it in the plugin repo also) as well as LINKED_PLUGIN_REPO=<abs path of local sentry-webpack-plugin repo>

[github-actions]

size-limit report

Path	Size
@sentry/browser - CDN Bundle (gzipped)	22.32 KB (-0.01% 🔽)
@sentry/browser - Webpack	23.3 KB (0%)
@sentry/react - Webpack	23.33 KB (0%)
@sentry/browser + @sentry/tracing - CDN Bundle (gzipped)	29.77 KB (-0.01% 🔽)

[kamilogorek]

Overall looks good, but I'm not sure if we need 2 checks everywhere.
One decides whether to link, second decides where to link. But the second argument is redundant without the first, and the first is redundant without the second. So maybe we can just use CLI_PATH and PLUGIN_PATH for both things? If it's present, link it, if it's not, then ignore it.
We can also optionally add [ ! -d $CLI_PATH ] && echo "CLI path $CLI_PATH does not exists" or similar check.

[lobsterkatie]

Overall looks good, but I'm not sure if we need 2 checks everywhere. One decides whether to link, second decides where to link. But the second argument is redundant without the first, and the first is redundant without the second. So maybe we can just use CLI_PATH and PLUGIN_PATH for both things? If it's present, link it, if it's not, then ignore it. We can also optionally add [ ! -d $CLI_PATH ] && echo "CLI path $CLI_PATH does not exists" or similar check.

Yeah, that's actually what I had at first (one variable for each repo), but then I couldn't find a good variable name for the combo, so I made it two. You're right that it's probably less of a pain to use if it's just one. I can switch it back.