Distribute prebuilt binaries via the npm registry #3750

- Remove all custom download logic for prebuilt binaries
- Add scripts to populate package contents
- Specify minimum versions of common package managers
- Remove sharp.vendor runtime API as no-longer relevant
- Update installation docs and issue templates

install/check.js

@@ -0,0 +1,27 @@
+// Copyright 2013 Lovell Fuller and others.
+// SPDX-License-Identifier: Apache-2.0
+
+'use strict';
+
+const { useGlobalLibvips, globalLibvipsVersion, log, gypRebuild } = require('../lib/libvips');
+
+const buildFromSource = (msg) => {
+  log(msg);
+  log('Attempting to build from source via node-gyp');
+  try {
+    require('node-gyp');
+  } catch (err) {
+    log('You might need to install node-gyp');
+    log('See https://sharp.pixelplumbing.com/install#building-from-source');
+  }
+  const status = gypRebuild();
+  if (status !== 0) {
+    process.exit(status);
+  }
+};
+
+if (process.env.npm_config_build_from_source) {
+  buildFromSource('Detected --build-from-source flag');
+} else if (useGlobalLibvips()) {
+  buildFromSource(`Detected globally-installed libvips v${globalLibvipsVersion()}`);
+}