Issue 4028 - Add support for Edge extensions to buildtools

docs/metadata.edge.example

 [default]
+# Base metadata file whose sections and keys we inherit but can override.
 inherit = metadata.common
 
-# App identity assigned by the Store.
-[package_identity]
-name = EyeoGmbH.AdblockPlus
-publisher = CN=4F066043-8AFE-41C9-B762-6C15E77E3F88
+# Icons to be placed into /Assets and referenced in AppxManifest.xml.
+[appx_assets]
+# 50x50 logo for the store.
+logo_50.png = path/to/logo_50.png
 
-# Icons to be placed in /Assets and referenced in AppxManifest.xml.
-[appx_assets]
-logo_44.png = chrome/icons/abp-38.png
-logo_50.png = chrome/icons/detailed/abp-48.png
-logo_150.png = adblockplusui/skin/abp-128.png
+# 44x44 and 150x150 logos for Windows UI.
+logo_44.png = path/to/logo_44.png
+logo_150.png = path/to/big_logo.png
 
 [compat]
+# Target Edge version (for manifest.json)
 edge = 37.14332.1000.0
+# Min/max windows version (for AppxManifest.xml)
+windows = 10.0.14332.0/12.0.0.0
 
 [general]
-basename = adblockplusedge
-display_name = Adblock Plus
-description = Adblock Plus is the most popular ad blocker ever, and also supports websites by not blocking unobstrusive ads by default (configurable).
-background_color = red
-extension_id = 1.0
-permissions = tabs
+# App identity and publisher ID assigned by the Windows Dev Center.
+app_id = ACME.MyExt
+publisher_id = CN=4F066043-8AFE-41C9-B762-6C15E77E3F88
+
+# Base name of the plugin file (version and extension will be added to this).
+basename = myext-edge
+
+# Background color for the Appx manifest.
+background_color = pink
+
+# Permissions of the extension to place into manifest.json
+# (see https://developer.chrome.com/extensions/declare_permissions).
+permissions =
+  tabs
+  bookmarks
   http://*/*
   https://*/*
-  contextMenus
-  webRequest
-  webRequestBlocking
-  webNavigation
-  storage
-  unlimitedStorage
-  notifications
+
+# UI definitions.
 options = options.html
-devtools = devtools.html
-browserAction = icons/abp-19.png icons/abp-38.png popup.html
-icons = icons/abp-16.png icons/abp-32.png icons/detailed/abp-48.png
-  icons/detailed/abp-64.png icons/detailed/abp-128.png
-managedStorageSchema = managed-storage-schema.json
 
+# Icon for the browser toolbar. Used to produce browser_action key in
+# manifest.json (see https://developer.chrome.com/extensions/browserAction).
+browserAction = icons/icon-19.png icons/icon-38.png popup.html
+
+# Icons for manifest.json.
+icons = icon-16.png icon-32.png icon-48.png icon-64.png icon-128.png
+
+# Files that are renamed/moved when placed into the package.
 [mapping]
-icons/abp-19.png = chrome/icons/abp-19.png
-icons/abp-19-whitelisted.png = chrome/icons/abp-19-whitelisted.png
-icons/abp-19-notification-critical.png = chrome/icons/abp-19-notification-critical.png
-icons/abp-19-notification-information.png = chrome/icons/abp-19-notification-information.png
-icons/abp-38.png = chrome/icons/abp-38.png
-icons/abp-38-whitelisted.png = chrome/icons/abp-38-whitelisted.png
-icons/abp-38-notification-critical.png = chrome/icons/abp-38-notification-critical.png
-icons/abp-38-notification-information.png = chrome/icons/abp-38-notification-information.png
-icons/detailed/abp-48.png = chrome/icons/detailed/abp-48.png
-ext/devtools.js = chrome/ext/devtools.js
-devtools.html = chrome/devtools.html
-devtools.js = chrome/devtools.js
-devtools-panel.html = adblockplusui/devtools-panel.html
-devtools-panel.js = adblockplusui/devtools-panel.js
-skin/devtools-panel.css = adblockplusui/skin/devtools-panel.css
-managed-storage-schema.json = chrome/managed-storage-schema.json
+target/path/file.png = source/path/icon.png
 
+# Javascript source files to be compiled/bundled by JSHydra.
 [convert_js]
-lib/adblockplus.js -= abp2blocklist/lib/abp2blocklist.js safari/contentBlocking.js
+# Two files bundled into one.
+path/bundle.js = source/path/src1.js src2.js
+
+# Remove a file from a bundle defined in common.metadata.
+path/common-bundle.js -= removed/src.js