[v4][regression] Default config paths changed comparing to v3 — plz recover .codecov.yml support

[webknjaz]

In v3, codecov/uploader was used and it had an excessive list of possible config locations (a matrix of different filenames and dirs). With v4 and codecov/codecov-cli, though, that list was replaced with just a single possibility.

In other words, codecov/codecov-action@v4 changed the config path defaults without telling anyone:

• https://github.com/codecov/uploader/blob/1e505ba8a27a1e3311a7a8db7f314e3705a2ee08/src/helpers/token.ts#L69-L76
• https://github.com/codecov/codecov-cli/blame/019a55a5e3c4c54fe587e318658fe093c304db99/codecov_cli/main.py#L38

The old defaults were to look up config filename variants with and without a leading dot, and with 3- and 4-letter extension variants, under the current working directory, .github/ subfolder and dev.

All my repos have the config in their respective roots called .codecov.yml, which worked without any problems for years across all the previous action versions v1/v2/v3 and with manual invocations before that.

With the upgrade to v4, it's not being detected:

warning - 2024-02-01 23:18:58,826 -- Config file codecov.yml not found, or is not a file. Ignoring config.

[thomasrockhu-codecov]

Closing in favor of codecov/codecov-cli#365