Update form navigation to use new v3SegmentedProgressBar

[oddball-lindsay]

Issue Description

There is a new v3 progress bar that has been tested and is ready for use.

Navigation currently in use: Private Zenhub Image

New v3 design: Private Zenhub Image

---

Tasks

• [x] Locate the v3 design in the codebase
• [x] Apply the v3 design to our forms

Acceptance Criteria

• [x] Form navigation has been updated to use the v3 design

[oddball-lindsay]

The v3 design system is located in src/platform/forms-system/src/js/components/FormNav.jsx

  const v3SegmentedProgressBar = formConfig?.v3SegmentedProgressBar;
  // show progress-bar and stepText only if hideFormNavProgress is falsy.
  return (
    <div>
      {!hideFormNavProgress && (
        <va-segmented-progress-bar
          total={chaptersLengthDisplay}
          current={currentChapterDisplay}
          uswds={v3SegmentedProgressBar}
          heading-text={chapterName ?? ''} // functionality only available for v3
          {...(v3SegmentedProgressBar ? { 'header-level': '2' } : {})}
        />
      )}
      {!v3SegmentedProgressBar &&
        !hideFormNavProgress && (
          <div className="schemaform-chapter-progress">
            <div className="nav-header nav-header-schemaform">
              {showHeader ? (
                <h2
                  id="nav-form-header"
                  data-testid="navFormHeader"
                  className="vads-u-font-size--h4"
                >
                  {stepText}
                  {inProgressMessage}
                </h2>
              ) : (
                <div data-testid="navFormDiv" className="vads-u-font-size--h4">
                  {stepText}
                  {inProgressMessage}
                </div>
              )}
            </div>
          </div>
        )}
    </div>
  );

A few other forms are also using this v3 design:

[holdenhinkle]

PR - https://github.com/department-of-veterans-affairs/vets-website/pull/26178