util/docker/alpine: Rename Dockerfile to Dockerfile.base

Rename Dockerfile to Dockerfile.base since additional Dockerfiles basing
on this one will be added later.

Change-Id: I611feca234ae7600f9c17ae397f9f3903879c057
Signed-off-by: Felix Singer <felixsinger@posteo.net>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79362
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin L Roth <gaumless@gmail.com>

util/docker/alpine/Dockerfile.base

@@ -0,0 +1,27 @@
+FROM alpine:edge
+
+RUN apk update && apk upgrade
+
+RUN apk add \
+	bash \
+	bison \
+	build-base \
+	bzip2 \
+	curl \
+	flex \
+	gcc-gnat \
+	git \
+	go \
+	htop \
+	linux-headers \
+	m4 \
+	ncurses-dev \
+	neovim \
+	openssl-dev \
+	py3-pip \
+	python3 \
+	tar \
+	tmux \
+	shadow \
+	xz \
+	zlib-dev