add onTap event

[astheras]

for example

SubstringHighlight(
    text: 'txt_agreement'.tr,
    terms: [
      'txt_terms_conditions'.tr,
      'txt_privacy_policy'.tr,
    ],
    textAlign: TextAlign.center,
    textStyle: Get.textTheme.headline2!.copyWith(
      fontSize: 12,
      fontWeight: FontWeight.w400,
      letterSpacing: 0,
    ),
    textStyleHighlight: Get.textTheme.bodyText2!.copyWith(
      fontSize: 12,
      fontWeight: FontWeight.w400,
      letterSpacing: 0,
      color: AppColors.accentPrimary,
   ),
    onTap :  (String termName){
       if (termName== 'txt_terms_conditions'.tr, ) ....
   }
)