client/service: refactor group param of spawn into an Enum (#10248)

* refractored group param to enum

* refractored group param to enum

* changed group param to GroupName enum for other methods too such as spawn_inner
updated docs

* revert on task type

* put back ticks in GroupName

* Update client/service/src/task_manager/mod.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* document group name
change specific to actual in enum declaration

* change documentation

* Update client/service/src/task_manager/mod.rs

Co-authored-by: Andronik Ordian <write@reusable.software>

* changed Actual to Specific

* Update client/service/src/task_manager/mod.rs

Co-authored-by: Andronik Ordian <write@reusable.software>

* Update client/service/src/task_manager/mod.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update client/service/src/task_manager/mod.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update client/service/src/task_manager/mod.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

Co-authored-by: Damilare <dakinlose@teamapt.com>
Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>
Co-authored-by: Andronik Ordian <write@reusable.software>