[C++][FlightRPC][ODBC] Add instructions to run ODBC tests to `README`

[alinaliBQ]

Describe the enhancement requested

• Add instructions to run ODBC unit and remote tests, so folks in the community can run the tests on their local Windows machines

Parent issue: #30622

Component(s)

FlightRPC, C++

[lidavidm]

Issue resolved by pull request 48835
#48835