dockerimg: add commonly requested packages to Dockerfile.base and enable :latest tagging

Add commonly requested packages to the Sketch Docker base image based on user installation
patterns, and update pushdockerimg.go to also tag images with :latest for easier access.

Co-Authored-By: sketch <hello@sketch.dev>
Change-ID: sd9eedb6795403819k
diff --git a/dockerimg/testdata/testcreatedockerfile_basic_repo_with_readme.dockerfile b/dockerimg/testdata/testcreatedockerfile_basic_repo_with_readme.dockerfile
index 8938524..75ac856 100644
--- a/dockerimg/testdata/testcreatedockerfile_basic_repo_with_readme.dockerfile
+++ b/dockerimg/testdata/testcreatedockerfile_basic_repo_with_readme.dockerfile
@@ -1,4 +1,4 @@
-FROM ghcr.io/boldsoftware/sketch:741e5a2d5a35c7fb3282a265bdd0cf24
+FROM ghcr.io/boldsoftware/sketch:82c32883426c519eada7250c0017e6b7
 
 ARG GIT_USER_EMAIL
 ARG GIT_USER_NAME
@@ -7,7 +7,7 @@
     git config --global user.name "$GIT_USER_NAME" && \
     git config --global http.postBuffer 524288000
 
-LABEL sketch_context="36e4db4d24da7f95d8bf1a3a97378381619077dbd3cb62163e2823ad2e97d286"
+LABEL sketch_context="b0ea3946bf71afcf3ab66a04750a8cc0e3c73e5395cadc8511bfdd7577d92bf5"
 COPY . /app
 RUN rm -f /app/tmp-sketch-dockerfile