client: add bitcoin plugin, update custom build deps

Adds bitcoin building plugin and finance image build dependencies.

See the code documentation in this commit for details.

client/docker-finance.d/client/Dockerfiles/finance/Dockerfile.archlinux.in

@@ -54,6 +54,18 @@ RUN pacman -Syu --noconfirm
 #WORKDIR /home/@DOCKER_FINANCE_USER@
 #RUN pipx install xlsx2csv
 
+##
+## Plugins (dependencies)
+##
+
+## libbitcoinkernel (bitcoin)
+#RUN pacman -Syu \
+#  boost \
+#  capnproto \
+#  cmake \
+#  db \
+#  --noconfirm --disable-download-timeout
+
 ## Add yours below, as needed