Change `<model>` `metaid` in all models

[dilpath]

Currently varies, with values like COPASI0, arFramework3, or the model name. Seen in #153

Possible options:

• the model name
• benchmark_models_petab

metaid and annotation attributes are described in the SBML specification [1], section 6.3 (page 101).

[1] http://co.mbine.org/specifications/sbml.level-3.version-2.core.release-2.pdf