Increase control over output metadata (#3856)

Add withX and keepX functions to take advantage of
libvips 8.15.0 new 'keep' metadata feature.

test/types/sharp.test-d.ts

@@ -659,6 +659,18 @@ sharp('input.tiff').webp({ preset: 'drawing' }).toFile('out.webp');
 sharp('input.tiff').webp({ preset: 'text' }).toFile('out.webp');
 sharp('input.tiff').webp({ preset: 'default' }).toFile('out.webp');
 
-// Allow a boolean or an object for metadata options.
-// https://github.com/lovell/sharp/issues/3822
-sharp(input).withMetadata().withMetadata({}).withMetadata(false);
+sharp(input)
+  .keepExif()
+  .withExif({
+    IFD0: {
+      k1: 'v1'
+    }
+  })
+  .withExifMerge({
+    IFD1: {
+      k2: 'v2'
+    }
+  })
+  .keepIccProfile()
+  .withIccProfile('filename')
+  .withIccProfile('filename', { attach: false });