User agent will be set as "genai-toolbox/" + versionString.
Instead of a panic, Toolbox will throw an error if the source fail to
retrieve `user agent`.
This will also be consistent with setting and getting logger from
context.
Fixes#291 by throwing a more descriptive error when items field is not provided.
Example of error when `items` field not provided for array parameter:
```
2025-02-18T14:07:58.77173-08:00 ERROR "unable to parse tool file at \"tools.yaml\": unable to parse as \"postgres-sql\": unable to parse as \"array\": unable to parse 'items' field: error parsing parameters: nothing to unmarshal"
```
This only checks within `SourceConfig`, `ToolConfig`, and
`AuthSourceConfig`.
Error when an unknown field is provided:
`2025-01-27T22:43:46.988401-08:00 ERROR "unable to parse tool file at
\"tools.yaml\": unable to parse as \"cloud-sql-postgres\": [2:1] unknown
field \"extra\"\n 1 | database: test_database\n> 2 | extra: here\n ^\n 3
| instance: toolbox-cloudsql\n 4 | kind: cloud-sql-postgres\n 5 |
password: postgres\n 6 | "`
Error when a required field is not provided:
`2025-01-27T17:49:47.584846-08:00 ERROR "unable to parse tool file at
\"tools.yaml\": validation failed: Key: 'Config.Region' Error:Field
validation for 'Region' failed on the 'required' tag"`
---------
Co-authored-by: Kurtis Van Gent <31518063+kurtisvg@users.noreply.github.com>
Add user agent to cloud databases that provides us anonymized data
request count, number of users, number of projects, and other
environment settings.
User agent is using the format: `genai-toolbox/$version+metadata`
