Add missing merge clauses in DeltaTableWriter

[riccamini]

Description

DeltaTableWriter provides the option to configure the writer in MERGE mode using the output_mode_params field by providing in it a list of merge clauses in the merge_builder key. This is especially useful in case the Delta table or the DataFrame to be merged are not available upfront. Not all merge clauses were supported: the merge clause provided was being validated against a list of valid clauses which did not include whenMatchedUpdateAll and whenNotMatchedInsertAll clauses. As part of this PR:

• validation of the clauses now happens in the output_mode_params field validator (currently this is happening only when the merge is being executed)
• the list of available merge clauses is sourced directly from available methods in DeltaMergeBuilder class and now includes all of them

Related Issue

#43

Motivation and Context

Now it's possible to use all merge clauses when configuring the DeltaTableWriter

How Has This Been Tested?

Tests covering validation errors have been added

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[dannymeijer]

LGTM 🚀