Closes # (if applicable).

Fix bugs in reserve constraint

This PR should fix to bugs in the operational reserve constraint.

1. bug: when formulating the lhs of the constraint it is summed over the time steps not the generators
2. bug: for the additional constraint that reserve + dispatch < capacity the sign is the wrong way around

This PR does not fix the issue that this constraint only works for the power sector.

Checklist

• I tested my contribution locally and it seems to work fine.
• Code and workflow changes are sufficiently documented.
• Changed dependencies are added to envs/environment.yaml.
• Changes in configuration options are added in all of config.default.yaml.
• Changes in configuration options are also documented in doc/configtables/*.csv.
• A release note doc/release_notes.rst is added.