Making test codes for react components

[KSoonYo]

Main idea

Making test codes for:

• react components

Alternative ideas

No response

Anything else?

No response

### Tasks
- [x] add scripts for testing react components in package.json
- [x] Flex
- [x] DoubleTag
- [ ] FlexActivityIndicator
- [ ] Information
- [ ] ProjectResourcePolicySettingModal
- [ ] ProjectSelector
- [ ] UserInfoModal
- [ ] VFolderSelect
- [ ] SessionList
- [ ] UserSelector

[KSoonYo]

@yomybaby I changed this issue because I thought testing react components with Jest is more important than 'summary page' web components. Would it be ok?