Service Catalog AppRegistry application construct initial base version.
Please note the ARNS for this construct have two '/' in them hence the slightly
different ARN parsing

Testing done
------------------
* `yarn build && yarn test`
* `yarn integ`

Co-authored-by: Dillon Ponzo <dponzo18@gmail.com>

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Addressing comments from PR

Co-authored-by: Dillon Ponzo <dponzo18@gmail.com>

Addressing minor formatting comments from PR review.
Added functionality to skip validation if we are passed a token for properties,
and added unit tests for those cases

Testing done
------------------
* `yarn build && yarn lint && yarn test`

Co-authored-by: Dillon Ponzo <dponzo18@gmail.com>

Updating unit tests to properly test that token inputs do
end up getting created in template and not just validating it throwing
a specific error

Testing done
------------------
* `yarn build && yarn lint && yarn test`

Co-authored-by Dillon Ponzo <dponzo18@gmail.com>

… into appregistry_l2_construct

merging branch

Co-authored-by: Adam Ruka <adamruka85@gmail.com>

…n.ts

Co-authored-by: Adam Ruka <adamruka85@gmail.com>