Remove deprecated querystring dependency.

[dompuiu]

Description

Remove the querystring dependency. It is deprecated and no longer maintained.

Related Issue

Motivation and Context

alloy uses @adobe/reactor-query-string as a dependency. We added a custom build script for alloy. When we run that script with npx, we see a warning saying that querystring is deprecated. We want to get rid of that warning. This PR uses URLSearchParams. I added a few tests to make sure the change is backward compatible.

A few of the differences between querystring and URLSearchParams can be found here.

Even if the changes should be compatible, I will release these as a new major version.

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.