`FlatObjectField` will benefit from using `IndexOrDocValuesQuery`

[harshavamsi]

Is your feature request related to a problem? Please describe.
Similar to the efforts in #7057 and #11144, FlatObjectField has a bunch of MultiTermQueries that will benefit from being able to search documents when only doc_values is enabled and using IndexOrDocValuesQuery when it has both index and doc_values enabled.

Describe the solution you'd like
If only index is enabled, we return the existing query. If both index and doc_values are enabled we return a wrapped IndexOrDocValuesQuery. If only doc_values are enabled, we probably use SortedSetDocValuesField.newXyzQuery for range, fuzzy etc

Describe alternatives you've considered
Do nothing.

[harshavamsi]

@mingshl I created this issue to track the work for FlatObjectField.

[macohen]

@mingshl are you able to pick this up? If you're able, awesome, otherwise I think this should be unassigned or assigned to someone else.

[mingshl]

I have no problem picking this up. I saw a flat-object PR #11425 is up, and I would love to raise the new one after it's merged.