refactor(users): Deprecate unused user APIs and stabilize v1 APIs

[ThisIsMani]

Type of Change

• [ ] Bugfix
• [ ] New feature
• [ ] Enhancement
• [x] Refactoring
• [ ] Dependency updates
• [ ] Documentation
• [ ] CI/CD

Description

Deletions

• /user/switch_merchant
• /user/switch/list
• /user/merchants/list
• /user/merchant_select/list
• /user/permission_info

Modifications

• /user/user will work same as /user/user/v2
• /user/user/list will work same as /user/user/v2/list
• /user/user/invite/accept will work same as /user/user/invite/accept/v2
• /user/user/invite/accept/pre_auth will work same as /user/user/invite/accept/pre_auth
• /user/role/list will work same as /user/role/v2/list

Additional Changes

• [x] This PR modifies the API contract
• [ ] This PR modifies the database schema
• [ ] This PR modifies application configuration/environment variables

Motivation and Context

Closes #6112.

How did you test it?

All the below APIs with throw 404.

• /user/switch_merchant
• /user/switch/list
• /user/merchants/list
• /user/merchant_select/list
• /user/permission_info

All the below APIs with behave differently.

• /user/user will work same as /user/user/v2
• /user/user/list will work same as /user/user/v2/list
• /user/user/invite/accept will work same as /user/user/invite/accept/v2
• /user/user/invite/accept/pre_auth will work same as /user/user/invite/accept/pre_auth
• /user/role/list will work same as /user/role/v2/list

Checklist

• [x] I formatted the code cargo +nightly fmt --all
• [x] I addressed lints thrown by cargo clippy
• [x] I reviewed the submitted code
• [ ] I added unit tests for my changes where possible