Live build log in the terminal

At the moment it is rather cumbersome to watch live logs from builds with copr-cli - even though copr-cli returns returns a link to the build, one needs to click it manually and then hunt the link for the actual live build log. Also as far as I can tell the log file does not refresh automatically (like for example the live build log file does on OBS) and one has to refresh it manually.

This is especially cumbersome for packages that take a while to build as even though the the copr-cli output does inform you of the build finishing/failing, it is much less noticeable than a live log in the terminal stopping with error. Also an error can be easily inspected in this case, rather than hunting for the link and then finding the log file & inspecting it for the error message.

How this could work
This should likely by optional & will require user input anyway in case the build runs on multiple chroots to set which log should be shown.

So I propose adding a new option --show-build-log to the copr-cli build sub-command:

• if --show-build-log is passed and the build runs on a single chroot, the live build log from this chroot would be shown in the terminal
• the --show-build-log option can also be used to pass chroot name, to select which log should be shown in case of multi-chroot builds, for example:

copr-cli build osm-scout-server --show-build-log=fedora-30-x86_64 valhalla-3.0.8-8.fc30.src.rpm

• if --show-build-log is passed without chroot name and the build runs on multiple chroots one is selected automatically (say by lexicographical ordering), alternatively this could fail with error either if it is possible to detect beforehand if a build will run on multiple chroots or simply always if no chroot name is passed to --show-build-log (pretty much depends on what is the most convenient to implement in copr-cli)

• if --show-build-logis not passed, nothing changes from the current behavior