[feat] Add PyTorch Profiler. (#5560)

* add profiler

* add profiler

* update

* resolve flake8

* update doc

* update changelog

* clean doc

* delete prof file

* merge pr codebase

* update

* update doc

* update doc

* update doc

* update on comments

* update docstring

* update docstring

* try

* update test

* Update pytorch_lightning/profiler/__init__.py

Co-authored-by: Jirka Borovec <Borda@users.noreply.github.com>

* Update pytorch_lightning/profiler/__init__.py

Co-authored-by: Jirka Borovec <Borda@users.noreply.github.com>

* update on comments

* remove old code

* add support for ddp

* resolve flake8

* Update pytorch_lightning/profiler/__init__.py

Co-authored-by: Sean Naren <sean.narenthiran@gmail.com>

* resolve tests

* resolve flake8

Co-authored-by: Jirka Borovec <jirka.borovec@seznam.cz>
Co-authored-by: Jirka Borovec <Borda@users.noreply.github.com>
Co-authored-by: Sean Naren <sean.narenthiran@gmail.com>