Missing show/hide-fields command in :save-session-to

[ConorMurphy21]

lnav version
I believe latest

Describe the bug
:save-session writes a list of commands, including :show-fields and hide-fields to a json file in the lnav home directory. But when calling :save-session-to which produces an lnav file, these commands are not added to the output session file.

To Reproduce

1. run :hide-fields body command
2. run :save-session-to /tmp/sesh.lnav
3. Observer no :hide-fields body in the /tmp/sesh.lnav