EXIF improvements and bugfixes

- Fixes a writing issue for float values ​​less than 1
- Fixes a missing definition of `EXIF_DATETIMEDIGITIZED` tag
- Adds support for some common camera shot metadata
- Adds missing metadata to writing tests

The following plugins automatically gain support for the new metadata: AVIF, IFF, HEIF, JXL, JXR, PSD and TGA (V2E).

The new metadata added with this patch is usually saved by smartphones (e.g. iPhone or Google Pixel).

autotests/writetest.cpp

@@ -62,7 +62,7 @@ void setOptionalInfo(QImage &image, const QString &suffix)
 
     // Set metadata
     auto meta = obj.value("metadata").toArray();
-    for (auto jv : meta) {
+    for (auto &&jv : meta) {
         auto obj = jv.toObject();
         auto key = obj.value("key").toString();
         auto val = obj.value("value").toString();
@@ -106,7 +106,7 @@ bool checkOptionalInfo(QImage &image, const QString &suffix)
 
     // Test metadata
     auto meta = obj.value("metadata").toArray();
-    for (auto jv : meta) {
+    for (auto &&jv : meta) {
         auto obj = jv.toObject();
         auto key = obj.value("key").toString();
         auto val = obj.value("value").toString();