Closes #475

Changes proposed in this Pull Request

Implements endogenous road transport. Interaction between elec and lpg vehicles is the user can select one of:

• must_run_evs: True - In this scenario, both p_min_pu and p_max_pu are set to match the load profile. LPG has no limits.
• must_run_evs: False - In this scenario p_min_pu of both elec and lpg are set to zero. p_max_pu of both elec and lpg are set to match the load profile.

Im not really sure what one is better, so the option to select one or the other exists right now. Documentation of transportation is coming soon in a seperate PR.

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.