fix: Improve behaviour of highlight dates with swapRange

[ilchenkoArtem]

Description

Linked issue: #5258

Problem
When I open a date range picker with swapRange, I select the first date. Then, when I hover or focus on the second date, if the second date is before the first date, all dates within this range do not have the following in range classes: react-datepicker__day--in-selecting-range, react-datepicker__day--selecting-range-start, react-datepicker__day--selecting-range-end.

Screen.Recording.2025-08-19.at.13.44.46.mov

Changes

• All days within the selected range now correctly receive the in range classes.
• The classes react-datepicker__day--selecting-range-start and react-datepicker__day--selecting-range-end are now dynamically setted based on selectionDate and startDate, but only when the swapRange prop is enabled.

Screenshots

Screen.Recording.2025-08-19.at.13.45.13.mov

To reviewers

Contribution checklist

• I have followed the contributing guidelines.
• I have added sufficient test coverage for my changes.
• I have formatted my code with Prettier and checked for linting issues with ESLint for code readability.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.23%. Comparing base (cf2eaa1) to head (0b685f0).
⚠️ Report is 7 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5800   +/-   ##
=======================================
  Coverage   97.23%   97.23%           
=======================================
  Files          30       30           
  Lines        3435     3442    +7     
  Branches     1440     1457   +17     
=======================================
+ Hits         3340     3347    +7     
  Misses         95       95           

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