chore: sync project files to match upstream templates (#4537)

- updated some files to match the official CodeIgniter 4 skeleton.
- rebuilt package.json from a clean init and modernized metadata and formatting
- rebuilt composer.json with modernized metadata and formatting
- replaced code of conduct text with markdown
- updated Dockerfile to replace deprecated instruction

package.json

@@ -1,34 +1,33 @@
 {
     "name": "@opensourcepos/opensourcepos",
     "version": "3.4.2",
-    "description": "pen Source Point of Sale is a web based point of sale system written in the PHP language. It uses MySQL as the data storage back-end and has a simple user interface.",
-    "main": "index.php",
-    "license": "MIT",
-    "authors": [
-        "jekkos <jekkos - at - opensourcepos.org>",
-        "FrancescoUK <francesco.lodolo.uk - at - gmail.com>",
-        "objecttothis <objecttothis - at - gmail.com>",
-        "SteveIreland <stevei - at - ruledomain.com>"
-    ],
-    "files": [
-        "dist/opensourcepos.$version.tgz"
-    ],
-    "publishConfig": {
-        "registry": "https://npm.pkg.github.com/"
-    },
+    "description": "Open Source Point of Sale is a web based point of sale system written in the PHP language. It uses MySQL as the data storage back-end and has a simple user interface.",
     "keywords": [
         "point-of-sale",
         "POS"
     ],
+    "homepage": "https://opensourcepos.org",
+    "bugs": {
+        "url": "https://github.com/opensourcepos/opensourcepos/issues"
+    },
     "repository": {
         "type": "git",
-        "url": "https://github.com/opensourcepos/opensourcepos"
+        "url": "git+https://github.com/opensourcepos/opensourcepos.git"
     },
+    "license": "MIT",
+    "contributors": [
+        "jekkos <jekkos - at - opensourcepos.org>",
+        "objecttothis <objecttothis - at - gmail.com>"
+    ],
+    "files": [
+        "dist/opensourcepos.$version.tgz"
+    ],
+    "type": "module",
+    "main": "index.php",
     "scripts": {
         "build": "gulp default",
         "gulp": "gulp"
     },
-    "type": "module",
     "dependencies": {
         "bootstrap": "^3.4.1",
         "bootstrap-daterangepicker": "^2.1.27",
@@ -82,5 +81,8 @@
         "npm-check-updates": "^22.1.1",
         "readable-stream": "^4.4.2",
         "stream-series": "^0.1.1"
+    },
+    "publishConfig": {
+        "registry": "https://npm.pkg.github.com/"
     }
 }