Add proximity filters to legal searches with More keyword options modal

[JonellaCulmer]

What we're after

Develop a front-end implementation of the legal proximity search feature based on the provided design. The UI should allow users to input legal terms, specify proximity parameters, and display relevant results.

Dev notes

• Primary keyword or phrase input: A text field where users can input keyword or phrases. They can add multiple keyword or phrase text fields (currently no limit to how many they can add). Uses q_proximity. These fields must be used with max_gaps.
• Maximum proximity: A text field where users can input a numeric value for the number of words between keywords. max_gaps can only be used with primary keyword. Required field.
• Secondary keyword or phrase: A text field where users can input keyword or phrase. They can only put in one at a time. Uses proximity_filter_term. This is an option field. You must use this field with the proximity_filter.
• Appears: A drop down field that is coupled and required with the secondary keyword or phrase. Options are: before all primary terms or after all primary terms. Uses proximity_filter.

Completion criteria

• Legal data users can now filter words or phrases based on proximity

Designs

Modal "more keyword options" design - #6592 (comment)