[docs]: Add federated search to docs

[belbiy]

Description

This PR adds the federated search feature to the docs site. You now can search for Devdocs, User Guide and OMS docs from PWA docs.

I would also like to commit Gemfile.lock file as we do on devdocs, since it's better way to manage the updates to theme and other gems this way.

Verification Steps

1. Go to the docs site
2. Search for something
3. Or go to search results page.
4. See the search results from different sites.

How Have YOU Tested this?

Screenshots / Screen Captures (if appropriate):

Proposed Labels for Change Type/Package

• major (e.g x.0.0 - a breaking change)
• minor (e.g 0.x.0 - a backwards compatible addition)
• patch (e.g 0.0.x - a bug fix)

Checklist:

• I have updated the documentation accordingly, if necessary.
• I have added tests to cover my changes, if necessary.

[magento-cicd2]

All committers have signed the CLA.

[vercel]

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Latest deployment for this branch: https://venia-git-fork-belbiy-ybadd-federated-search.magento-research1.now.sh

[jcalcaben]

This is on hold until @belbiy is ready to make this feature live on all doc sites

[PWAStudioBot]

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Log

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danger-results://tmp/danger-results.json

Generated by 🚫 dangerJS against 5634a76

[belbiy]

@jcalcaben , i'm ready to merge this if you don't mind. What's the next steps to do this?

[PWAStudioBot]

	Fails
🚫	No linked issue found. Please link a relevant open issue by adding the text "closes #<issue_number>" in your PR.

	Messages
📖	We are currently working on automating the PR metadata checks. Until that time, you may see failures related to labels/description/linked issues/etc even if you have fixed the problem. Failures will persist until the next push (assuming they are fixed).

Generated by 🚫 dangerJS against ce0ea5d

[jcalcaben]

Looks good to me

@dpatil-magento here are the verification steps I used:

1. Check out the latest from develop

   git fetch origin && git checkout origin/develop

2. Pull in the changes for this PR:

   git pull https://github.com/belbiy/pwa-studio.git yb_add-federated-search

3. Install new ruby dependencies

   bundle install

4. Install any new node dependencies

   npm install

5. Run preview server

    npm run develop

6. Navigate to the home page.
7. Type in a term in the search box such as "rest"
8. Verify that multiple results from the different devdoc sites appear
9. Submit the search term
10. Verify that you are on the search results page with the search results grouped in different tabs.