ci: test samples and examples with a packaged bolt build

[zimeg]

Summary

This PR explores broken builds due to missing @types/express from the most recent release 👀

> tsc --noemit --module commonjs --project ./tsconfig.json
node_modules/@slack/bolt/dist/receivers/ExpressReceiver.d.ts(9,98): error TS7016: Could not find a declaration file for module 'express'. '/home/runner/work/slack-sandbox/slack-sandbox/js.bolt.tails/node_modules/express/index.js' implicitly has an 'any' type.
  Try `npm i --save-dev @types/express` if it exists or add a new declaration (.d.ts) file containing `declare module 'express';`
node_modules/@slack/bolt/dist/receivers/ParamsIncomingMessage.d.ts(3,39): error TS2307: Cannot find module 'express-serve-static-core' or its corresponding type declarations.

Preview

• This test passes when using npm pack without removing node_modules
• This test fails when using npm pack and removing node_modules

Notes

• Moving @types/express back into dependencies seems like a fix to the above errors, but this was difficult to confirm with local setups. Hoping to improve our CI testing and return @types/express in perhaps another PR to prevent this regression in future changes 😓
• The PR isn't in a state to be merged right now, but I'm super interested in feedback on this testing approach!

Requirements

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.59%. Comparing base (d07a70a) to head (5ea64ca).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2372   +/-   ##
=======================================
  Coverage   92.59%   92.59%           
=======================================
  Files          36       36           
  Lines        7472     7472           
  Branches      653      653           
=======================================
  Hits         6919     6919           
  Misses        545      545           
  Partials        8        8           

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[zimeg]

📝 Leaving a few notes from findings during the most recent adventures. I'm so open to thoughts and changing the goal of this PR.

IMO testing samples with npm pack might be nice to split into a separate change, but I'm rambling now...

[zimeg]

Some TILs are included here, though I believe this can still be improved:

• npm pack will package @slack/bolt as if it's going to be released
• node_modules of the bolt-js repo must be removed or nested directories can make use of these pacakges

The *.tgz file seems ideal for testing in a production environment like this since it lets us build bolt-js then remove its node_modules before testing a sample!

I'm not thrilled with the relative paths here, but am interested in if this is an approach we're alright taking?

[zimeg]

Updating examples continues to be an upcoming task, but I found this app to be helpful for testing the current edges.

FWIW I'm interested in knowing if we want to include jsdoc as part of examples for typechecking like this or not? That can of course be for a follow up, but I think it might be neat 🔍

[zimeg]

TBH I think ParamsIncomingMessage should be exported at the top-level of @slack/bolt since it describes the "req" parameter of receivers, but that's unchanged in this PR.

However I'm super curious to know if exporting it from the top-level would fix the current typescript error here 🤔