[ENHANCEMENT]: Add insert overloads that take value_type as input

[PointKernel]

Is your feature request related to a problem? Please describe.

Firstly proposed by @sleeepyjack in #407 (comment)

The current heterogeneous insert feature requires users to pass an explicit pair type when invoking the device insert functions. So the legacy behavior like:

  set_ref.insert({key, payload});

is no longer supported.

Describe the solution you'd like

Similar to STL insert, it would be nice to add an overload of insert taking value_type as input thus the sample code can work as well.