Fix searching projects by handle

[maxceem]

In another issue, we've enabled searching projects by "handle" #421

Though, it appears the search by the handle is case-sensetive, but should be case-insensitive:

• open https://connect.topcoder-dev.com/projects
• there is project 8846 which has customers: TCConnCopilot, tcconnBDR, TCConCopilotMgr and managers: TCConAccountMgr, TCConManager, pshah_manager
• though we only can find this project when we are searching by manager pshah_manager, but cannot find it searching by customer or manager handles with upper-case letters.
• most likely it's due to using not_analyzed for the handle as we CAN find these projects using user name with upper-case letters https://github.com/topcoder-platform/tc-project-service/blob/cf21/src/utils/es-config.js#L244 which should be removed
• create 2 unit test which would check that searching by handle works case-insensitive:
  • find a project with a member with a lowercase handle using an upper-case filter
  • find a project with a member with an uppercase handle using a lower-case filter

[vikasrohit]

@maxceem Closing. Please feel free to make it open again if some work is pending.