feat: add method to retrieve name based on loginID

Author: becooq81

src/main/java/org/poolc/api/member/service/MemberService.java

@@ -226,6 +226,12 @@ public List<Member> getAllMembersAndUpdateMemberIsExcepted() {
         return members;
     }
 
+    public String findNameByLoginID(String loginID) {
+        Member member = memberRepository.findByLoginID(loginID)
+                .orElseThrow(() -> new NoSuchElementException("No member with given login ID."));
+        return member.getLoginID();
+    }
+
     private String resetMemberPasswordToken(String email) {
         Member resetMember = memberRepository.findByEmail(email)
                 .orElseThrow(() -> new NoSuchElementException("No user found with given email"));