fix: add undeclared dependency underscore

[merceyz]

Platforms affected

All

Motivation and Context

cordova-lib depends on underscore but doesn't declare it as a dependency

cordova-lib/src/cordova/serve.js

Line 24 in 5cc0a79

const { template, object: zipObject } = require('underscore');

cordova-lib/src/cordova/requirements.js

Line 20 in b9ad92a

const { object: zipObject } = require('underscore');

It was declared correctly before but seems to have been removed in #772

Ref apache/cordova-ios#1105

Description

Added underscore as a dependency

Testing

Ran cordova prepare under a strict dependency environment

Checklist

• I've run the tests to see all new and existing tests pass
• I added automated test coverage as appropriate for this change
• Commit is prefixed with (platform) if this change only applies to one platform (e.g. (android))
• If this Pull Request resolves an issue, I linked to the issue in the text above (and used the correct keyword to close issues using keywords)
• I've updated the documentation if necessary

[raphinesse]

Thanks a lot for spotting this and bringing it up here! I would rather remove the hidden dependency on underscore than to declare it (see #871). But let's see if someone else has an opinion on that.