More HEIF-related tests.

New option `KIMAGEFORMATS_HEIC_TEST` for testing images with
HEVC codec only.

Existing option `KIMAGEFORMATS_HEIF_TEST` is used for testing other
possible (mostly quite rare) codecs that might be used by HEIF
images - uncompressed, deflate, zlib, brotli, jpeg.

autotests/read/heic/metadata.heic.json

@@ -0,0 +1,65 @@
+[
+    {
+        "fileName" : "metadata.png",
+        "colorSpace" : {
+            "description" : "sRGB build-in",
+            "primaries" : "SRgb",
+            "transferFunction" : "SRgb",
+            "gamma" : 0
+        },
+        "metadata" : [
+            {
+                "key" : "ModificationDate",
+                "value" : "2025-02-26T16:52:06Z"
+            },
+            {
+                "key" : "Software" ,
+                "value" : "LIFE Pro 2.18.10 (Linux)"
+            },
+            {
+                "key" : "Altitude",
+                "value" : "34"
+            },
+            {
+                "key" : "Author",
+                "value" : "KDE Project"
+            },
+            {
+                "key" : "Copyright",
+                "value" : "@2025 KDE Project"
+            },
+            {
+                "key" : "Description",
+                "value" : "TV broadcast test image."
+            },
+            {
+                "key" : "Latitude",
+                "value" : "44.6478"
+            },
+            {
+                "key" : "LensManufacturer",
+                "value" : "KDE Glasses"
+            },
+            {
+                "key" : "LensModel",
+                "value" : "A1234"
+            },
+            {
+                "key" : "Longitude",
+                "value" : "10.9254"
+            },
+            {
+                "key" : "Manufacturer",
+                "value" : "KFramework"
+            },
+            {
+                "key" : "Model",
+                "value" : "KImageFormats"
+            }
+        ],
+        "resolution" : {
+            "dotsPerMeterX" : 11811,
+            "dotsPerMeterY" : 5905
+        }
+    }
+]