column presets need not have type

Currently, column presets take an option `static` or `from session variable`. This is inconsistent with the permission builder where we assume anything like `X-Hasura-` is a session variable and rest is static. This convention seems normal and will simplify the column presets section in insert/update permissions.


The issue does not name a file or test. Start by locating the column-presets controls and permission-builder handling for static versus session-variable values; verify the convention is applied consistently in insert and update permissions and that column presets no longer require a separate type.

Written by the indexing model from the issue text.