Support using a pre-installed `codecov` binary

[veehaitch]

Currently, the action always downloads the codecov-cli binary:

https://github.com/codecov/codecov-action/blob/a9883cc0b21bfacae39d8ccace5c36d00ed01ece/src/index.ts#L42

This causes trouble in some environments where networking access is restricted (also see #700) or if the action should use a specific version of the binary (e.g., an audited version built from source).

Adding a new argument to action.yml which allows giving an absolute path to the binary would be very helpful.

[thomasrockhu-codecov]

@veehaitch this is a great idea. I'm a little bit slammed at the moment, but I will work on adding this in sometime this month

[veehaitch]

Any update on this, @thomasrockhu-codecov? 🙂

[thomasrockhu-codecov]

@veehaitch gah, time really has caught up to me. Let me see what I can do this week, thanks for following up @veehaitch

[veehaitch]

Great, thanks for the quick response!

[thomasrockhu-codecov]

@veehaitch I haven't forgotten about this, we are considering a different architecture to the action that may make this easier to do.

[veehaitch]

Hey @thomasrockhu-codecov, I just wanted to check in and see if you were still working on that issue. Thanks!