[libvirt] [PATCH 00/14] Support reading auth credentials from a config file

When connecting to a remote libvirtd, or hypervisor that requires authentication we have callbacks which can be used to prompt for various credentials. This is tedious if you are looking to automate stuff though. While we could let each application implement a custom auth callback for fetching credentials from a config file, it is nicer if we provide this ability directly in libvirt, so that all apps can benefit from it. So this series introduces a new config file in which authentication credentials can be placed. It supports setting multiple sets of credentials, of varying types in one file. I use the '.ini' config file syntax, since this makes it easy to reuse the same config file in virt-viewer & similar apps to store VNC / SPICE credentials. To find the config file we check for each of - Path from LIBVIRT_AUTH_FILE env var - Query param 'authfile=PATH' in the URI params - /etc/libvirt/auth.conf - $HOME/.libvirt/auth.conf if no config file is present, everything should carry on as normal. If the config is present, then it is consulted to fill in credentials first. Only if there are still missing credentials, will the auth callbacks then be invoked. See the docs in patch 12 of this series for the config file syntax examples. This is supported for all drivers that do auth, remote, esx, xenapi, hyperv and phyp, though I have only tested it with the remote driver. I would appreciate someone giving it a go with the other drivers. The first 7 patches are actually all related to the viruri.[ch] file, expanding its functionality & adding tests. This is to make sure the auth config patches can have easy access to the query params. The last 7 patches are related to the auth config file support again including tests