fix: add missing overrides to the supabase generator

[devj3ns]

This PR sits on top of #420, which fixed some generator issues as described in #416.

It specifically resolves the following errors:

The Customer model has no onConflict specified in the SupabaseSerializable, which results in the following runtime error because of the missing override:

lib/brick/adapters/customer_adapter.g.dart:102:7: Error: The non-abstract class 'CustomerAdapter' is missing implementations for these members:
 - SupabaseAdapter.onConflict

The WindowType model has no SupabaseSerializable specified (because there is no corresponding Supabase table, it is used inside a JSONB field), and therefore the tableName is null, which results in the following runtime error because of the missing override:

lib/brick/adapters/window_type_adapter.g.dart:98:7: Error: The non-abstract class 'WindowTypeAdapter' is missing implementations for these members:
 - SupabaseAdapter.supabaseTableName

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I just noticed that the supabaseTableName is a non-nullable field on the SupabaseAdapter, which means this PR is not ready as it is. @tshedor how should we handle this?