CLOUDSTACK-7908: Add user_id column to vm_instance table

- Adds column to VMInstance DAO
- Adds column in vm_instance table
- Adds column in the UserVMJoinVO
- Adds default admin user which has UID = 2
- Adds migration path that sets user_id to first user of the accountId that
  owns the vm in vm_instance table
- Add arg on list VMs API to query by userId, add support in query layer
- Refactor VMInstanceVO and child classes to accept userId
- Add code to let service layer pass userId if loggedIn user belongs to same
  account as the owner executing an API call or use first user from owner account
- In case of CPVM and SSVM use system user ID
- Fix unit tests and spring injections

Signed-off-by: Rohit Yadav <rohit.yadav@shapeblue.com>