Online tournaments fixes

[ctizen]

• Add selector to admin panel to select platform type (for superadmin only as majsoul events are not widely adoptable)
• Remove "Add online game" button for majsoul events
• Check input log format and throw an error if 'log' field is missing. Ideally, check by json schema.
• Restrict access or hide particular admin panel pages (e.g. game controls do not make sense)