perf(term): add benchmarks

Adds benchmarks by running [alacritty/vtebench](https://github.com/alacritty/vtebench)
benchmarks in the terminal.
Uses code based on [godotengine/godot-benchmarks](https://github.com/godotengine/godot-benchmarks)
to measure average GPU and CPU time spent per frame.
Uses [github-action-benchmark](https://github.com/benchmark-action/github-action-benchmark)
for continuous integration, and publishes benchmark results to https://lihop.github.io/godot-xterm/dev/bench/.

benchmark/editor_launch.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+set -e
+
+godot=${1:-godot}
+
+if ! command -v $godot &> /dev/null; then
+    echo "Error: '$godot' command not found. Please provide a valid path to the Godot executable."
+    exit 1
+fi
+
+results_file=benchmark/results/editor_launch.json
+value=$({ time -p $godot --editor --quit; } 2>&1 | tail -n3 | head -n1 | cut -d' ' -f2)
+cat <<EOF > $results_file
+[
+    {
+        "name": "editor_launch",
+        "unit": "seconds",
+	    "value": $value
+    }
+]
+EOF
+cat $results_file
+