Front Door and Express Route extensions.

[tjprescott]

Moves Front Door and Express Route extensions into public extensions repo. Updates Front Door for help text changes.

---

This checklist is used to make sure that common guidelines for a pull request are followed.

General Guidelines

• Have you run ./scripts/ci/test_static.sh locally? (pip install pylint flake8 required)
• Have you run python scripts/ci/test_index.py -q locally?

For new extensions:

• My extension description/summary conforms to the Extension Summary Guidelines.

[azuresdkci]

If this PR is for a new extension or change to an existing extension, use the following to try out the changes in this PR:

docker run -it microsoft/azure-cli:latest
export EXT=<NAME>
pip install --upgrade --target ~/.azure/cliextensions/$EXT "git+https://github.com/tjprescott/azure-cli-extensions.git@MovePrivateExtensions#subdirectory=src/$EXT&egg=$EXT"

[williexu]

Are you publishing express routes too?

[tjprescott]

It is already published. The Front Door extension needed a version bump because the help text changed.

[williexu]

Why are there so many visual studio files added? are they all necessary?

[tjprescott]

Intentionally, to support @yugangw-msft and my effort to make developing for extensions the same as the regular CLI. That means have a VS proj and sln file.

[williexu]

there's 6 added visual studio related files?..

[tjprescott]

What can I say--it's visual studio 🤷‍♂️

[tjprescott]

I cut back on the number of commit VS files. It should be 4 now.