feat(oldgalois): add theme (#11880)

themes/oldgallois.zsh-theme

+# Depends on the git plugin for work_in_progress()
+(( $+functions[work_in_progress] )) || work_in_progress() {}
+
+ZSH_THEME_GIT_PROMPT_PREFIX="%{$reset_color%}%{$fg[green]%}["
+ZSH_THEME_GIT_PROMPT_SUFFIX="]%{$reset_color%}"
+ZSH_THEME_GIT_PROMPT_DIRTY="%{$fg[red]%}*%{$reset_color%}"
+ZSH_THEME_GIT_PROMPT_CLEAN=""
+
+# Customized git status, oh-my-zsh currently does not allow render dirty status before branch
+git_custom_status() {
+  local branch=$(git_current_branch)
+  [[ -n "$branch" ]] || return 0
+  echo "$(parse_git_dirty)\
+%{${fg_bold[yellow]}%}$(work_in_progress)%{$reset_color%}\
+${ZSH_THEME_GIT_PROMPT_PREFIX}${branch}${ZSH_THEME_GIT_PROMPT_SUFFIX}"
+}
+
+# RVM component of prompt
+ZSH_THEME_RUBY_PROMPT_PREFIX="%{$fg[red]%}["
+ZSH_THEME_RUBY_PROMPT_SUFFIX="]%{$reset_color%}"
+
+# Combine it all into a final right-side prompt
+RPS1="\$(git_custom_status)\$(ruby_prompt_info)${RPS1:+ $RPS1}"
+PROMPT='%{$fg[cyan]%}[%~% ]%(?.%{$fg[green]%}.%{$fg[red]%})%B$%b '