Root-198: add search-as-you-type suggestion query functionality

[jesconstantine]

This PR adds the following functionality:

• the solr client can now handle an event that should trigger a "suggest" query and dispatches an action with the necessary payload, based on autocomplete configuration (which comes from the implementing app)
• two new reducers will handle setting the state of the "suggest" query (which pulls some values from the regular search query for things like credentials, filters, facets) and setting the state of the suggestion results
• two new functions will handle building the "suggest" query
• the "server" will perform a new xhr request for making the "suggest" query and dispatch the appropriate action and payload to on of the new reducers
• this new functionality has added test coverage

This PR also makes the solr client un-opinionated about default / query fields, relying on the implementation's solr config to set these. This allows flexibility with the default search, autocomplete, and enables field boosting to be set in solr config.

Main and autocomplete queries are now sent with q=<mainQueryField.value> as opposed to q=tm_rendered_item:<mainQueryField.value> and q=<mainQueryField.value>+<mainQueryField.value>*&df=mainQueryField.field respectively.

To test

1. See corresponding PR in the app repo which has updated its package.json to pull from this branch and follow that PR's test steps for functional test
2. Run tests in this repo by pulling down this branch and running yarn test, observe that all tests pass
3. See the test output for buildSuggestQuery, solrSuggestQuery, suggestQueryReducer, suggestionsReducer for a high level understanding of what the new code does (as of now, this will likely change a bit this week)

TODO

1. Alter the suggest query to either a) accept configuration for choosing a query parser + query fields or b) only send the search term and rely on solr config to handle everything else

[jesconstantine]

Tested heavily by @agentrickard in PRs referenced above. Merging!