Motivation:
  - We are looking to build out a notebook viewer with an eye toward performance.
    In our flamegraph research we found that as much as 90% of the time spent in
    Notebook creation can occur in the preprocessor valdiation logic. This pr
    introduces the optional idea of optimistic validation, in which we care not
    about which preprocessor introduces a validation error but that the notebook
    ends in a valid state, since we care more about speed.

Related Issues:
  - #1663

Changes:
  - Introduces a config option to remove some of the validation checks.

Questions:
  - I am new to the project and am not sure where a test should live for
    this logic, or the best way to structure such a test. If a reference
    is available I will happily added a test.

I primarily want to allow for the possibility of line numbers
in HTML output. Pygments supports this natively, but we don't
have a way to pass arguments through to pygments.

A traitlet is added to allow passing arbitrary extra args
to the Pygments formatter, for Html and LaTeX. Should allow for
line number control and much more :)

This has been something folks have asked for for a while.

Ref ipython/ipython#5847
Ref #427
Ref yuvipanda/notebooksharing.space#34

Pandoc >= 2.11.1 requires the calc package, and pandoc >= 2.11.3
requires the array package, for larger tables (taken from git blame
for pandoc's templates).  This commits adds the two packages in
an order similar to that in pandoc's templates.

* Add an invalid notebook error
Motivation:
  - As we are now service hundreds of thousands of notebooks a day, we are
    seeing a number of errors from Notebook rendering that really stem
    from notebooks not being properly formated. These show up in a number
    of errors such as the error handled in this pr, an assertion error,
    we have also seen key errors and others. This pr is a bit of a proposal
    to instead introduced a common exception that indicates the notebook
    is missing some required data that is needed to render itself.

* Update nbconvert/filters/markdown_mistune.py

Co-authored-by: Matthias Bussonnier <[email protected]>

Co-authored-by: Matthias Bussonnier <[email protected]>

* fix use of deprecated API and add python 3.10 test

* test on pypy

* fix syntax

* clean up pypy

* expand test matrix

* cleanup

* cleanup

* fix install

* fix windows test

* fix windows test

* fix windows test

* fix windows test

* fix windows test

* fix excludes

* fix tests on py310

* cleanup

* cleanup

The generated html file was not following the 'classic' template, but instead 'lab', when I ran the code according to documentaion. But when I passed the template_name as a keyword arguement to HTMLExporter it worked. So I made necessary changes to the code, in a way which worked for me. Please do a review of the code and accept the changes