Allow to specify template when running dagger project init

Adds the ability to select a template which will create a new file
in the CWD with the template name. Templates present in the
"cmd/dagger/project/templates" directory are automatically embedded in the dagger
binary when building and then listed in the `dagger project init` help output.

Usage:

    dagger project init -t <template_name>

One idea that we had while pairing on this is to eventually try
improving this UX by extending the `dagger project` command by adding
sub-commands like `dagger project templates [list, new, output, ...]`.

Pair: gerhard

Signed-off-by: Marcos Lilljedahl <marcosnils@gmail.com>

tests/package.json

@@ -4,7 +4,7 @@
     "test": "bats --jobs 4 --print-output-on-failure --verbose-run ."
   },
   "devDependencies": {
-    "bats": "https://github.com/bats-core/bats-core#master",
+    "bats": "https://github.com/bats-core/bats-core#v1.6.0",
     "bats-assert": "https://github.com/bats-core/bats-assert",
     "bats-support": "https://github.com/bats-core/bats-support"
   }

tests/project.bats

@@ -8,7 +8,7 @@ setup() {
 }
 
 @test "project init and update and info" {
-	cd "$TEMPDIR" || exit
+	cd "$TEMPDIR" || exit 1
 
 	"$DAGGER" project init ./ --name "github.com/foo/bar"
 	test -d ./cue.mod/pkg
@@ -39,3 +39,27 @@ setup() {
 	assert_failure
 	assert_output --partial "dagger project not found. Run \`dagger project init\`"
 }
+
+
+@test "project init with template" {
+  cd "$TEMPDIR" || exit 1
+
+  if test -f ./hello.cue
+  then
+    echo "./hello.cue should not exist"
+    exit 1
+  fi
+
+  run "$DAGGER" project init -t hello
+
+  assert_success
+
+  if test ! -f ./hello.cue
+  then
+    echo "./hello.cue file was not created by the template flag"
+    exit 1
+  fi
+
+  cd -
+  diff --unified "$TEMPDIR/hello.cue" "$TESTDIR/../cmd/dagger/cmd/project/templates/hello.cue"
+}