aerc: Add configuration to replace neomutt usage

Starting to replace neomutt in my workflow with aerc:
it is a little more lightweight, directly supports notmuch directories
and has a relatively sane configuration style (mostly just ini-like)
with 'go-templating' baked in.

In general, the configuration just feels less 'cobbled-together' than
before. I can make changes without worrying what other things are going
to break by doing so. I understand the complete configuration and
styling, instead of mostly relying on other people's formatting lines
for the styles.

I am still learning some of the configuration possibilities but it
already functions as a neomutt replacement.

office/.config/aerc/aerc.conf

@@ -0,0 +1,68 @@
+[general]
+enable-osc8 = true
+
+[ui]
+dirlist-tree = true
+fuzzy-complete = true
+dialog-position = bottom
+
+styleset-name = simple
+
+index-columns = flags>4,name<20%,subject,date>=
+this-week-time-format = Mon 02
+sidebar-width = 15
+
+threading-enabled = true
+reverse-thread-order = true
+show-thread-context = true
+thread-prefix-folded = "+ "
+thread-prefix-tip = ""
+thread-prefix-indent = ""
+thread-prefix-stem = "│"
+thread-prefix-limb = "─"
+thread-prefix-folded = "+"
+thread-prefix-unfolded = ""
+thread-prefix-first-child = "┬"
+thread-prefix-has-siblings = "├"
+thread-prefix-orphan = "┌"
+thread-prefix-dummy = "┬"
+thread-prefix-lone = " "
+thread-prefix-last-sibling = "╰"
+
+[statusline]
+column-left = [{{.Account}}] {{cwd}} {{.ContentInfo}}
+column-right = {{.TrayInfo}} | {{dateFormat now "Mon Jan 2 15:04:05 2006"}}
+
+[viewer]
+
+[compose]
+file-picker-cmd = vifm --choose-files -
+reply-to-self = false
+empty-subject-warning = true
+no-attachment-warning = ^[^>]*(attach(ed|ment)|an(ge)?hang)
+
+[multipart-converters]
+text/html=pandoc -f commonmark_x -t html --standalone --embed-resources --template email
+# TODO: change to djot when new pandoc version in repos
+
+[filters]
+.filename,~.*.ics = calendar
+text/plain                              = wrap -w 100 | colorize
+text/calendar                           = calendar
+message/delivery-status                 = colorize
+message/rfc822                          = colorize
+text/html                               = pandoc -f html -t plain
+application/pdf                         = pdftotext - -l 10 -nopgbrk -q - | wrap -w 100
+application/msword                      = pandoc -f docx -t plain
+application/vnd.openxmlformats-officedocument.wordprocessingml.document = pandoc -f docx -t plain
+application/vnd.oasis.opendocument.text = pandoc -f odt -t plain
+.headers                                = colorize
+# text/html                             = ! html # ! for interactive applications
+
+[openers]
+# does not have filename checking for openers?
+.filename,~.*.ics = wezterm -e nvim -
+
+[hooks]
+
+[templates]