API simplification 2

[gogonzo]

2. Simplify calling a teal app

• API simplification: teal::init could accept a data.frame-like objects passed to its data parameter teal#49
• API simplification: data_extract_spec does not need filter_spec and select_spec definitions to provide defaults teal#51
• Default value for all arguments of teal::module teal#535
• https://github.com/insightsengineering/coredev-tasks/issues/338
• Reproducible metadata attribute teal.data#76
• datalabel should be a raw dataset attribute teal.data#77
• Add examples of apps with simplified UI teal.transform#24
• Design data extract and data merge #36
• Deprecate datasets in teal teal#656
• optional reporter in the independent teal modules teal#678