Address Subversion plaintext password saving

[penguian]

Reported by Scott Wales on 2023-03-15:

Subversion authentication can get into a bad state if a user's previously tried to use plaintext password saving. A fix is to recreate the file ~/.subversion/auth/svn.simple/2be6a67d04b1c8c6d879daafa52fd762, it should contain

K 8
passtype
V 9
gpg-agent
K 15
svn:realmstring
V 51
https://code.metoffice.gov.uk:443 Met Office Code
K 8
username
V {len(user)}
{user}
END

Could a check for this be added to mosrs-auth?

[create-issue-branch]

Branch issue-104-Address_Subversion_plaintext_password_saving created!