build: create gitpod.yml

This allows `git-branchless` to be developed and executed in the cloud.

Author: arxanas

.gitpod.yml

@@ -0,0 +1,7 @@
+image:
+  file: .gitpod/Dockerfile
+tasks:
+  - init: cargo build --tests && cargo install --path . && git branchless init
+vscode:
+  extensions:
+    - "matklad.rust-analyzer"

.gitpod/Dockerfile

@@ -0,0 +1,5 @@
+FROM gitpod/workspace-full
+
+# The following environment variables are necessary for `cargo test` to pass.
+# Determined by running `which git` and `git --exec-path`.
+ENV PATH_TO_GIT=/usr/bin/git GIT_EXEC_PATH=/usr/lib/git-core

.vscode/settings.json

@@ -1,4 +1,5 @@
 {
     "editor.formatOnSave": true,
-    "editor.formatOnType": true
+    "editor.formatOnType": true,
+    "files.insertFinalNewline": true
 }