setup code completion

Author: dpomier

.devcontainer/Dockerfile

@@ -1,3 +1,7 @@
 FROM haxe:4.3.6-gllr AS build-stage
 
-RUN mkdir $HAXE_COMPILER_DIR/plugins/ecso/
+RUN mkdir $HAXE_COMPILER_DIR/plugins/ecso/
+
+RUN set -ex ;\
+	cd $HAXE_COMPILER_DIR ;\
+	opam install ocaml-lsp-server ocamlformat

.vscode/tasks.json

@@ -10,7 +10,7 @@
                 "kind": "build",
                 "isDefault": true
             },
-            "command": "opam config exec -- make -s -j`nproc` STATICLINK=1 ADD_REVISION=1 PLUGIN=ecso plugin",
+            "command": "opam config exec -- make -s -j`nproc` STATICLINK=1 ADD_REVISION=1 && opam config exec -- make -s -j`nproc` STATICLINK=1 ADD_REVISION=1 PLUGIN=ecso plugin",
             "options": {
                 "cwd": "${workspaceFolder}/../.."
             }