Add fish completion support (#4605)

test/lib/common.fish

@@ -0,0 +1,17 @@
+# Unset fzf variables
+set -e FZF_DEFAULT_COMMAND FZF_DEFAULT_OPTS FZF_DEFAULT_OPTS_FILE FZF_TMUX FZF_TMUX_OPTS
+set -e FZF_CTRL_T_COMMAND FZF_CTRL_T_OPTS FZF_ALT_C_COMMAND FZF_ALT_C_OPTS FZF_CTRL_R_OPTS
+set -e FZF_API_KEY
+# Unset completion-specific variables
+set -e FZF_COMPLETION_TRIGGER FZF_COMPLETION_OPTS
+
+set -gx FZF_DEFAULT_OPTS "--no-scrollbar --pointer '>' --marker '>'"
+set -gx FZF_COMPLETION_TRIGGER '++'
+set -gx fish_history fzf_test
+
+# Add fzf to PATH
+fish_add_path <%= BASE %>/bin
+
+# Source key bindings and completion
+source "<%= BASE %>/shell/key-bindings.fish"
+source "<%= BASE %>/shell/completion.fish"