Sections marked with ::group::{title} should be able to request to not be collapsed

Copied from original issue: actions/runner#1036

Using the ::group::{title} and ::endgroup:: commands are useful to collapse verbose output or add section “headers” to the logs. However, sometimes after creating the group it is discovered that the group should not be collapsed and that it should be shown to the user.

A good example of this would be after a test fails:

Screenshot from 2021-04-02 11-57-02

Obviously a user who has experience with the GitHub actions UI and also tox in this situation, would know they should expand the grouped log lines above. In this simple example it is rather obvious which lines should be expanded, but this may not always be the case if the logs are long or the grouping is inconsistent or poorly named.

For this use case it would be great if the workflow author could write something like ::group-expand:: in order to force the UI to expand the log lines. This command could be valid until the ::endgroup:: command is issued, and as it is unlikely that a workflow author would need to change their mind about to show or not to show the group so there would not need to be a ::group-collapse:: command.

If this is not possible, an inferior solution would be to have a ::cancelgroup:: command which would act as the ::endgroup:: command, but remove any log grouping which was previously requested.