add legal date formats

[tmpayton]

Summary (required)

• Resolves Closing and Opening date range filters break with type or sort added #5531

This PR fixes the issue we are having with legal dates. These changes somehow got lost when rolling back the initial Flask deployment and deploying the flask hotfix. Here is the previous PR #5489

Required reviewers 1-2 developers

Impacted areas of the application

General components of the application that this PR will affect:

• legal.py

How to test

This can be tested locally or on dev

local:

1. Follow the wiki to setup and test elastic search locally
2. flask run
3. Test date fields under the legal search endpoint including:

• af_max_fd_date
• af_min_fd_date
• af_max_rtb_date
• af_min_rtb_date
• case_max_close_date
• case_min_close_date
• case_max_open_date
• case_min_open_date
• ao_max_request_date
• ao_min_request_date
• ao_max_issue_date
• ao_min_issue_date

on stage:
Test date filters on legal search pages

example urls:
https://stage.fec.gov/data/legal/search/murs/?search_type=murs&sort=-case_no&search=&case_no=&case_respondents=&case_min_open_date=&case_max_open_date=&case_min_close_date=06%2F06%2F2023&case_max_close_date=07%2F06%2F2023

[codecov]

Codecov Report

Merging #5533 (a6521e4) into release/public-20230808 (1e56b9a) will decrease coverage by 0.09%.
The diff coverage is 11.11%.

@@                     Coverage Diff                     @@
##           release/public-20230808    #5533      +/-   ##
===========================================================
- Coverage                    85.58%   85.50%   -0.09%     
===========================================================
  Files                           81       81              
  Lines                         8228     8237       +9     
===========================================================
+ Hits                          7042     7043       +1     
- Misses                        1186     1194       +8     

Files Changed	Coverage Δ
webservices/resources/legal.py	62.22% <11.11%> (-1.51%)	⬇️

[fec-jli]

Looks good. Thanks

[cnlucas]

Tested on stage and works for me 👍🏻