fix: correct package manager selection in CLI install

[aychtang]

• Because this PR includes a bug fix, relevant tests have been included.
  (It seems there are no existing tests for the CLI installation yet, so I have kept the same level of testing for now and added my manual test below).
• The change was previously discussed on an Issue or with someone from the team.

Description:

• (issue Support pnpm dlx hardhat --init #6111) Franco noticed that the install script defaults to using npm in some cases, noting that its probably to do with checking the directories package manager related files.
• Confirmed that the checks in project-creation.ts are checking for related .lock files, and therefore if the project isn't set up correctly then the CLI could use the wrong package manager.
• Added a new function getProjectTypeFromUserAgent which extracts the first part of process.env.npm_config_user_agent, this is then added as the first check in the isYarnProject and isPnpmProject functions.
• Note: This also removes the need to make a file system check in most cases.
• Note: process.env.npm_config_user_agent might not be available on all OS, and we still default back to initial behaviour for now.
• Rebuilt, packaged, and tested the change by printing the results of getProjectTypeFromUserAgent at start of CLI code.

Manual CLI test output:

howardtang hardhat-test % pnpm dlx $(pwd)/hardhat-2.22.19.tgz init
 WARN  3 deprecated subdependencies found: [email protected], [email protected], [email protected]
Packages: +243
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Progress: resolved 243, reused 242, downloaded 1, added 243, done
aychtang/hardhat
userAgent pnpm/8.8.0 npm/? node/v20.8.0 darwin arm64
projectType pnpm

[changeset-bot]

🦋 Changeset detected

Latest commit: add0158

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
hardhat	Patch

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Name	Status	Preview	Comments	Updated (UTC)
hardhat	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Mar 11, 2025 9:20pm

[galargh]

Great job! Thank you for your contribution 🙇 I allowed myself to add a changeset to your PR. Once the CI is through, I'm going to merge this 🚀