This function takes in a set of groups, and their consituent
channels and writes the appropriate .mbsyncrc block. The block is as
shown below:
Group groupName1
Channel channelName1
Channel channelName2
Group groupName2
Channel channelName3
Each group must have a unique name, no matter which account it is
declared under. The same holds true for channels. However, if there is
a group that shares the same name as the channel, the channel will
effectively be "shadowed" by the group, and mbsync will default to
working with the group in that case.
This change makes use of the `extend` function inside `lib` to inject
a new `hm` field containing the Home Manager library functions. This
simplifies use of the Home Manager library in the modules and reduces
the risk of accidental infinite recursion.
PR #994
To allow supporting more advanced configurations. The local refers to
the "maildir store" configuration, remote to the "IMAP store", and
"channel" to the channel.
This reworks the way program specific email account options are
specified. In particular, we no longer use the deprecated `options`
field of `mkOption`. Instead submodules are used.
