feat: 新增多个服务类及工具类，重构部分代码结构

重构服务类结构，将分散的服务统一整合到service包下
新增ProjectConstant常量类及多个实体服务类
添加SecurityUtils安全工具类和BeanCacher工具类
优化部分UI控件和转换器的实现

client/src/main/java/com/ecep/contract/service/CompanyBankAccountService.java

@@ -0,0 +1,14 @@
+package com.ecep.contract.service;
+
+import java.util.List;
+
+import com.ecep.contract.model.Company;
+import com.ecep.contract.model.CompanyBankAccount;
+import com.ecep.contract.vm.CompanyBankAccountViewModel;
+
+public class CompanyBankAccountService implements ViewModelService<CompanyBankAccount, CompanyBankAccountViewModel> {
+
+    public List<CompanyBankAccount> searchByCompany(Company company, String searchText) {
+        throw new UnsupportedOperationException("未实现");
+    }
+}