SOLR-17927: Rename llm, neural etc.

[chatman]

https://issues.apache.org/jira/browse/SOLR-17927

[chatman]

https://github.com/apache/solr/tree/main/solr/modules/llm

https://github.com/apache/solr/tree/main/solr/core/src/java/org/apache/solr/search/neural

[chaitali-rajhans]

Committed the code changes to support legacy fields and renamed fields ((hnswMaxConnections, hnswBeamWidth) -> (hnswM, hnswEfConstruction)) on top of existing PR, I'll get an initial review done for the same.