Added dialog for saving patch (web app)

Now a dialog will appear when we save patch instead of the default browser prompt. Fixes #866

Demo:

ubuntu__Running__-_Oracle_VM_VirtualBox_2022-02-27_15-55-48_Trim

Note: I have used data-bs... classes instead of data-... class because of Bootstrap 5. Current version of purr-data uses Bootstrap 4 which I have updated in !813