refactor: request headers include x-nacelle-sdk-version

[NWRichmond]

Why are these changes introduced?

Addresses ENG-9576

Send package version in 'x-nacelle-sdk-version' header

What is this pull request doing?

1. Adds an x-nacelle-sdk-version header to requests. This matches @nacelle/storefront-sdk@1.x behavior.
2. Moves the handling of endpoint query params and headers to new static methods. This allows us to simplify the constructor and the setConfig method.

How to Test

1. Check out the ENG-9576/send-package-version-in-x-nacelle-sdk-version-header branch
2. Navigate to packages/storefront-sdk
3. npm run build - the package should build without errors
4. npm run coverage - all test should pass with 100% coverage

Checklist

• This Pull Request aligns with nacelle-js' Code of Conduct.
• You can follow your own "How to Test" instructions and get the expected result.
• Created a changeset (if the change should appear in a changelog).

[changeset-bot]

🦋 Changeset detected

Latest commit: 3f84197

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

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
nacelle-gatsby-reference-store	✅ Ready (Inspect)	Visit Preview		May 1, 2023 2:28pm
nacelle-gatsby-starter	✅ Ready (Inspect)	Visit Preview		May 1, 2023 2:28pm
nacelle-next-reference-store	✅ Ready (Inspect)	Visit Preview		May 1, 2023 2:28pm
nacelle-next-starter	✅ Ready (Inspect)	Visit Preview		May 1, 2023 2:28pm
nacelle-nuxt-reference-store	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	May 1, 2023 2:28pm
nacelle-nuxt-starter	✅ Ready (Inspect)	Visit Preview		May 1, 2023 2:28pm

[KrisQ]

Looks good!