Allow heat-venting in all heating systems and impose small penalty for water tank chargers

[amos-schledorn]

Changes proposed in this Pull Request

This PR

• allows heat-venting in all heating systems through system-type-specific config settings.
• introduces marginal costs on heat-venting and water tank chargers (in the future also pit storage chargers).
• renames the config setting config.sector.marginal_cost_storage to config.sector.marginal_cost_home_battery_storage for clarity
• slightly improves the docs of gas boiler must run conditions

This should avoid artificial heat-venting through water tank charging/discharging at efficiencies < 1 (c.f. #1546)

Checklist

• I tested my contribution locally and it works as intended.
• Code and workflow changes are sufficiently documented.
• Changed dependencies are added to envs/environment.yaml.
• Changes in configuration options are added in config/config.default.yaml.
• Changes in configuration options are documented in doc/configtables/*.csv.
• Sources of newly added data are documented in doc/data_sources.rst.
• A release note doc/release_notes.rst is added.

Testing

• Tested with test/config.perfect.yaml. Artificial heat-venting through water tank charging/discharging is fully removed.

[amos-schledorn]

@fneum I've implemented this following our discussion but I'm not totally happy. Ideally, we would use the config.cost.marginal_cost setting.
Though that's only used in add_electricity but not in prepare_sector_network. What do you think?
If we stick to the current implementation, we should probably, to avoid confusion, rename config.sector.marginal_cost_storage which currently only modifies marginal costs for distribution grid batteries.