dev/core#1602 fix join_date filter in search builder

[lcdservices]

Overview

In search builder, the Member Since field is ignored.

Before

1. visit Search > Search Builder
2. select: Members > Member Since > = > (enter a date)
3. returns all records

After

Filtered by member since (join_date) field. Search result qil should also show that the filter is applied.

Technical Details

join_date needs to be handled in the same way as start_date and end_date in the membership query BAO.

[civibot]

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[seamuslee001]

closing in favour of #16578