[Feat]: Data Source Authentication Type - OAuth2

[saturn4er]

Is your feature request related to a problem? Please describe.
Some APIs authorize requests using tokens from an OAuth2 API. For example, to use Squidex, you first generate a token by sending client ID and client secret to a specific endpoint. These tokens usually have a short TTL, so hardcoding them into Lowcoder is not practical. Currently, Lowcoder does not support using such data sources because there is no option to set “Authentication Type” of a data source to OAuth2 token.

Describe the solution you'd like
Add a new Authentication type “OAuth2” to data source.