🚀[FEA]: Name distributed utilities more appropriately

[akshaysubr]

Is this a new feature, an improvement, or a change to existing functionality?

Improvement

How would you describe the priority of this feature request

Medium

Please provide a clear description of problem you would like to solve.

Many distributed utilities are named as private functions, eg: _gather, when they shouldn't be private.

Describe any alternatives you have considered

See PR discussion here: https://github.com/NVIDIA/modulus/pull/92#discussion_r1282876987