SimpleQueryParser to support field filtering (aka Add field:text operator) [LUCENE-8565]

SimpleQueryParser lacks support for the `field:` operator for creating queries which operate on fields other than the default field. Seems like one can either get the parsed query to operate on a single field, or on ALL defined fields (+ weights). No support for specifying `field:value` in the query.

It probably wasn't forgotten, but rather left out for simplicity, but since we are using this QP implementation more and more (mostly through Elasticsearch) we thought it would be useful to have it in.

Seems like this is not too hard to pull off and I'll be happy to contribute a patch for it.

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Migrated from [LUCENE-8565](https://issues.apache.org/jira/browse/LUCENE-8565) by Itamar Syn-Hershko, updated Aug 16 2019
Pull requests: https://github.com/apache/lucene-solr/pull/498

Start with the SimpleQueryParser entry point and review its current handling of default and all-field queries. Trace how a field:value expression would be parsed and represented, then add coverage for field-specific queries and verify the existing parser behavior remains unchanged.

Written by the indexing model from the issue text.