Deprecate backend_name as parameter for TranspilerService

[jesus-talavera-ibm]

Deprecate backend_name as parameter for TranspilerService. It will be substituted by backend which will be a Backend object instead of a string

[malinjawi]

hey @jesus-talavera-ibm! I am looking forward to making contributions to this repo. Is this issue still valid? I would be happy to take it up.

[jesus-talavera-ibm]

Hi @malinjawi , thank you for your interest in contributing to this repo.
Currently we are working on migrating Transpiler Service and we prefer not to do any change or deprecation during the migration.