Add Devcontainer Support (#3777)

* add devcontainer files

* update postCreate

* add chmod for postCreate

* set CORES env variable to pass to build tool

* remove ssh functionality

* Move delete env file cmd to postStartCommand

* update how env file is done

* Update

- Move to older version of ubuntu for compatability
- Change vnc password to orca

.devcontainer/devcontainer.json

@@ -0,0 +1,51 @@
+{
+	"name": "OrcaSlicer",
+	"image": "mcr.microsoft.com/devcontainers/cpp:ubuntu-20.04",
+	"runArgs": ["--env-file", "/tmp/devcontainer.env"],
+    "features": {
+        "ghcr.io/devcontainers/features/desktop-lite:1": {
+			"password": "orca"
+		}
+    },
+	"customizations": {
+		"vscode": {
+			"settings": { 
+				"cmake.configureArgs": [
+					"-DSLIC3R_GTK=3",
+					"-DBBL_RELEASE_TO_PUBLIC=1",
+					"-DBBL_INTERNAL_TESTING=0",
+					"-DSLIC3R_STATIC=1",
+					"-DCMAKE_PREFIX_PATH=${workspaceFolder}/deps/build/destdir/usr/local"
+				],
+				"cmake.buildToolArgs": [
+					"-l${containerEnv:CORES}"
+				]
+			},
+			
+			// Add the IDs of extensions you want installed when the container is created.
+			"extensions": [
+				"ms-vscode.cmake-tools",
+				"ms-vscode.cpptools-extension-pack"
+			]
+		}
+	},
+	
+    "forwardPorts": [6080],
+	"portsAttributes": {
+		"6080": {
+			"label": "VNC web client (noVNC)",
+			"onAutoForward": "silent"
+		}
+    },
+	"otherPortsAttributes": {
+		"onAutoForward": "ignore"
+	},
+	
+	"initializeCommand": {
+		"Setup Temporary Env File": "echo \"CORES=`nproc --all`\" > /tmp/devcontainer.env"
+	},
+	"onCreateCommand": {
+		"Set postCreate executable flag": "chmod +x .devcontainer/postCreate.sh"
+	},
+	"postCreateCommand": "sudo .devcontainer/postCreate.sh"
+}

.devcontainer/postCreate.sh

@@ -0,0 +1,14 @@
+#!/bin/bash
+# Update and upgrade all system packages
+apt update
+apt upgrade -y          
+
+echo "-----------------------------------------"	
+echo "Running BuildLinux.sh with update flag..."
+echo "-----------------------------------------"	
+./BuildLinux.sh -u
+
+echo "------------------------------"
+echo "Installing missing packages..."
+echo "------------------------------"
+apt install -y libgl1-mesa-dev m4 autoconf libtool