SG-41548 Make saveFileDialog RV command permissions check optional (#1056)

### SG-41548 Make saveFileDialog RV command permissions check optional

### Linked issues
NA

### Describe the reason for the change.
Some Windows users reported that when using the saveFileDialog() RV
command and writing on a network drive with the appropriate write
permissions, RV was incorrectly reporting that the destination directory
was not writable by the user. We were not able to reproduce this issue
which would have allowed us to find the real cause of this issue.

### Summarize your change.
This commit makes the saveFileDialog RV command permissions check prior
to saving optional if the RV_SKIP_SAVE_FILE_DIALOG_PERMISSIONS_CHECK
environment variable is set and also adds a "Try to Save Anyway" button
if the permission check fails.
Note that if the directory of the saving operation is really not
writable, then the write operation will fail.
At least this will unblock users facing this issue which seams to be
Windows + Network drive specific.

### Describe what you have tested and on which operating system.
Successfuly tested by the Windows users facing this specific Windows +
Network drive issue.

### Add a list of changes, and note any that might need special
attention during the review.

### If possible, provide screenshots.

Signed-off-by: Bernard Laberge <bernard.laberge@autodesk.com>

Author: bernie-laberge

src/lib/app/RvCommon/MuUICommands.cpp

@@ -896,25 +896,35 @@ namespace Rv
                 v = pathConform(UTF8::qconvert(files.at(0)));
                 QFileInfo info(UTF8::qconvert(v.c_str()));
 
-                //
-                //  QFileInfo says a non-existant file is not writable, so have
-                //  to check the directory in that case.
-                //
-                const bool isDirWritable = TwkUtil::isWritable(UTF8::qconvert(info.absolutePath()).c_str());
-                const bool isFileWritable = TwkUtil::isWritable(v.c_str());
-                if ((!info.exists() && !isDirWritable) || (info.exists() && !isFileWritable))
+                // Allow skipping permissions check via environment variable
+                static const bool skipPermissionsCheck = (getenv("RV_SKIP_SAVE_FILE_DIALOG_PERMISSIONS_CHECK") != nullptr);
+                if (!skipPermissionsCheck)
                 {
-                    QString message = QString("File '") + UTF8::qconvert(v.c_str())
-                                      + "' is not writable; please check the permissions or "
-                                        "choose another location.";
-                    QMessageBox confirm(QMessageBox::Warning, "Permissions", message, QMessageBox::NoButton, rvDoc, Qt::Sheet);
-
-                    QPushButton* q1 = confirm.addButton("OK", QMessageBox::AcceptRole);
-                    confirm.setIcon(QMessageBox::Question);
-                    confirm.exec();
-                    v = "";
+                    //
+                    //  QFileInfo says a non-existant file is not writable, so have
+                    //  to check the directory in that case.
+                    //
+                    const bool isDirWritable = TwkUtil::isWritable(UTF8::qconvert(info.absolutePath()).c_str());
+                    const bool isFileWritable = TwkUtil::isWritable(v.c_str());
+
+                    if ((!info.exists() && !isDirWritable) || (info.exists() && !isFileWritable))
+                    {
+                        QString message = QString("File '") + UTF8::qconvert(v.c_str())
+                                          + "' is not writable; please check the permissions or "
+                                            "choose another location.";
+                        QMessageBox confirm(QMessageBox::Warning, "Permissions", message, QMessageBox::NoButton, rvDoc, Qt::Sheet);
+
+                        QPushButton* q1 = confirm.addButton("Try to Save Anyway", QMessageBox::AcceptRole);
+                        QPushButton* q2 = confirm.addButton("Choose Another Location", QMessageBox::RejectRole);
+                        confirm.setDefaultButton(q2);
+                        confirm.setIcon(QMessageBox::Question);
+                        confirm.exec();
+                        if (confirm.clickedButton() != q1)
+                            v = "";
+                    }
                 }
-                else if (info.exists())
+
+                if (info.exists())
                 {
                     QString message = QString("File '") + UTF8::qconvert(v.c_str()) + "' exists; overwrite ?";
                     QMessageBox confirm(QMessageBox::Warning, "Overwrite", message, QMessageBox::NoButton, rvDoc, Qt::Sheet);