Android always returns true from CanWrite

[bon-ami]

Checklist

• [X] I have searched the issue tracker for open issues that relate to the same problem, before opening a new one.
• [X] This issue only relates to a single bug. I will open new issues for any other problems.

Describe the bug

1. storage.CanWrite() always return true?
2. storage.Writer() cannot create a file to write?

I am not sure whether it is bug or I did not do it correctly.

How to reproduce

I can only create a writer if the file exists, or use dialog.ShowFileSave()

Screenshots

No response

Example code

// I can successfully storage.Writer() with sss="content://com.android.externalstorage.documents/document/primary%3A.cc%2Fl", which is file l under .cc on internal storage (/sdcard/), if file l exists. But following fails if file la does not exist.
        uri, err = storage.ParseURI(sss + "a")
        if err != nil { // not here
            return nil, err
        }
        if uri == nil { // not here
            return nil, err
        }
        b, err := storage.CanWrite(uri)
        if err != nil { // not here
            return nil, err
        } // b is true
        wr, err := storage.Writer(uri) // fails here

Fyne version

2.2.3

Go compiler version

1.18.4

Operating system

Android

Operating system version

Android 9

Additional Information

No response

[andydotxyz]

I think the issue here is that we cannot create files into the "content://" area (AFAIK). Updated to be a bug that CanWrite is returning true when it shouldn't