feat: add execute permission level for datadocs

[jij1949]

This PR adds a new permission level called "execute". This new permission level only applies to datadocs, not boards/lists.

Permissions granted by "execute" include:

• Change values of variables (not variable names, types, and cannot create new variables or delete variables)
• Run query cells (includes run all)
• All other read-only permissions

"Execute" permissions are set up to work with user groups as well, and qualify as more permissive than "read only" and less permissive than "edit" for permission inheritance purposes.