fix no autoloading journal for "filename.xopp" and "filename.xoj" problem (#3217)

* fix an autoloading journal problem

By default, if suppose we were to save a file "filename.pdf" as an xopp/xoj
file, it would save to "filename.xopp". But enabling Autloading journals
feature in Edit->Preferences->Load/Save doesn't detect "filename.xopp" or
"filename.xoj", while loading the pdf file and doesn't load the xopp/xoj
file. But it instead autoloads if the file were named as
"filename.pdf.xopp" or "filename.pdf.xoj". This is because Util::ClearExtensions
doesn't explicitly remove ".pdf" extension from the file path, but rather removes
".xoj" and ".xopp". Utils::ClearExtensions can be forced to remove ".pdf" extension by
passing the extension as the second argument to the function.
This commit implements that second argument and loads
"filename.xoj"/"filename.xopp" if autoloading is enabled.

* remove duplicated code with a loop

* resolve merge conflict

* apply clang format

* apply suggested changes

src/control/Control.cpp

@@ -2079,18 +2079,16 @@ auto Control::loadPdf(const fs::path& filepath, int scrollToPage) -> bool {
     LoadHandler loadHandler;
 
     if (settings->isAutoloadPdfXoj()) {
-        fs::path f = filepath;
-        Util::clearExtensions(f);
-        f += ".xopp";
-        Document* tmp = loadHandler.loadDocument(f);
-
-        if (tmp == nullptr) {
-            f = filepath;
-            Util::clearExtensions(f);
-            f += ".xoj";
+        Document* tmp;
+        const std::vector<std::string> exts = {".xopp", ".xoj", ".pdf.xopp", ".pdf.xoj"};
+        for (const std::string& ext: exts) {
+            fs::path f = filepath;
+            Util::clearExtensions(f, ".pdf");
+            f += ext;
             tmp = loadHandler.loadDocument(f);
+            if (tmp)
+                break;
         }
-
         if (tmp) {
             this->doc->lock();
             this->doc->clearDocument();