Feat: basic asset type support

[nhoening]

Description

• Hosts, devs and also users need asset type IDs to do their work, but we don't let them look them up (only way to see them is the new-asset form in the UI).
• New installations should get default asset types, but how to add them is not clear enough.

Closes #1637

• Added new API endpoint GET /assets/types
• Improved documentation for hosts & devs - they should use flexmeasures add inital-structure, which is where default types are being created.
• Fixed a small bug in that CLI command
• Added changelog item in documentation/changelog.rst
• API changelog entry, too

How to test

Run pytest -x

I added a fm-client function which uses the new endpoint, see FlexMeasures/flexmeasures-client#136.

Use this script to test:

import asyncio

from flexmeasures_client import FlexMeasuresClient

usr = "xxx"
pwd = "xxx"

async def main():
    client = FlexMeasuresClient(email=usr, password=pwd)

    print("Getting asset types ...")
    asset_types = await client.get_asset_types()
    print(f"Got {len(asset_types)} asset types:")
    print(asset_types)

    await client.close()


asyncio.run(main())

[read-the-docs-community]

Documentation build overview

📚 flexmeasures | 🛠️ Build #29345558 | 📁 Comparing 372a502 against latest (81d507f)

🔍 Preview build

Show files changed (11 files in total): 📝 11 modified | ➕ 0 added | ➖ 0 deleted

File	Status
changelog.html	📝 modified
genindex.html	📝 modified
http-routingtable.html	📝 modified
_autosummary/flexmeasures.api.v3_0.assets.html	📝 modified
_autosummary/flexmeasures.api.v3_0.health.html	📝 modified
api/change_log.html	📝 modified
api/v3_0.html	📝 modified
concepts/data-model.html	📝 modified
dev/setup-and-guidelines.html	📝 modified
host/data.html	📝 modified
host/installation.html	📝 modified

[VladIftime]

Looks good, and the comments are understandable and easy to follow!