Utils: Introduce a FilePath constructor from char arrays

Similar to QT_RESTRICTED_CAST_FROM_ASCII to avoid the need for
decorations in user code.

At the same time, drop some convenience constructors and functions
in CommandLine and Icon essentially serving the same purpose.

Change-Id: Ida4e5ac19c2da0a4298a97b2a8e1511d56bbb79d
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/libs/utils/commandline.cpp

@@ -1418,18 +1418,10 @@ QString ProcessArgs::toString() const
 
 CommandLine::CommandLine() = default;
 
-CommandLine::CommandLine(const QString &executable)
-    : m_executable(FilePath::fromString(executable))
-{}
-
 CommandLine::CommandLine(const FilePath &executable)
     : m_executable(executable)
 {}
 
-CommandLine::CommandLine(const QString &exe, const QStringList &args)
-    : CommandLine(FilePath::fromString(exe), args)
-{}
-
 CommandLine::CommandLine(const FilePath &exe, const QStringList &args)
     : m_executable(exe)
 {