feat(docs): enable search functionality

[wesleygrimes]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/ngrx/platform/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Documentation has been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[x] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

Closes #1860

What is the new behavior?

Re-enable search box on website

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[ngrxbot]

Preview docs changes for fdd1a8f at https://previews.ngrx.io/pr2020-fdd1a8f/

[ngrxbot]

Preview docs changes for 777ef72 at https://previews.ngrx.io/pr2020-777ef72/

[wesleygrimes]

So this has been an interesting journey. The problem is that aio-search-box needs to be nested underneath aio-top-menu in order for styling to work correctly. I went down the path of adding ng-content to aio-top-menu so that I can nest aio-search-box directly from app.component.ts and not have to refactor everything. That appears to work but then the tests fail with the following error:

AppComponent search click handling should show developer source view if the footer is clicked while holding the meta and alt keys FAILED
	TypeError: Failed to execute 'contains' on 'Node': parameter 1 is not of type 'Node'.
	    at http://localhost:9876/src/app/app.component.ts?:310:31
	    at Array.some (<anonymous>)
	    at QueryList.push../node_modules/@angular/core/fesm5/core.js.QueryList.some (http://localhost:9876/node_modules/@angular/core/fesm5/core.js?:15129:1)
	    at AppComponent../src/app/app.component.ts.AppComponent.onClick (http://localhost:9876/src/app/app.component.ts?:309:28)
	    at UserContext.<anonymous> (http://localhost:9876/src/app/app.component.spec.ts?:376:26)
	    at ZoneDelegate../node_modules/zone.js/dist/zone.js.ZoneDelegate.invoke (http://localhost:9876/node_modules/zone.js/dist/zone.js?:388:1)
	    at ProxyZoneSpec.push../node_modules/zone.js/dist/zone-testing.js.ProxyZoneSpec.onInvoke (http://localhost:9876/node_modules/zone.js/dist/zone-testing.js?:288:1)
	    at ZoneDelegate../node_modules/zone.js/dist/zone.js.ZoneDelegate.invoke (http://localhost:9876/node_modules/zone.js/dist/zone.js?:387:1)
	    at Zone../node_modules/zone.js/dist/zone.js.Zone.run (http://localhost:9876/node_modules/zone.js/dist/zone.js?:138:1)
	    at runInTestZone (http://localhost:9876/node_modules/zone.js/dist/zone-testing.js?:509:1)

This appears to have something to do with ng-content and event bubbling...

I can go down the path of actually moving aio-search-box down a level into aio-top-menu but that will require a decent amount of refactoring due to how search results are tied into the main app component.

Any thoughts?

As an aside, the Angular.io website, which this is based upon, has the aio-search-box at the top level because their top-nav is left aligned. The NgRx top-nav is right aligned so it doesn't quite work the same. We could also right align the nav, but that would be a change.

[ngrxbot]

Preview docs changes for 36a0281 at https://previews.ngrx.io/pr2020-36a0281/

[ngrxbot]

Preview docs changes for 07eea44 at https://previews.ngrx.io/pr2020-07eea44/

[ngrxbot]

Preview docs changes for 2f89a42 at https://previews.ngrx.io/pr2020-2f89a42/

[ngrxbot]

Preview docs changes for d446b79 at https://previews.ngrx.io/pr2020-d446b79/