Postgres source: consider renaming `schema` and `table` options

[morsapaes]

The schema option takes a list of strings, so it'd be less confusing to call it schemas (= FOR SCHEMAS). The same is true for table (= FOR TABLES).

Not sure if there's a way to change this in a backwards-compatible way. It might be worth double-checking if there are similar examples and patch them all in one go.

[dehume]

Will compile the list of singular vs plural attribute names. We do have situations where we use the singular for an attribute but allow multiple blocks, but that is usually just for nested elements like columns in a table.

resource "materialize_table" "simple_table" {
  name          = "simple_table"
  column {
    name = "column_1"
    type = "text"
  }
  column {
    name    = "column_2"
    type    = "int"
  }

[dehume]

Lists For attributes that use list, we have more cases of singular than plural.

Attribute	Resource	Type	Plural
availability_zones	materialize_connection_aws_privatelink	List of Strings	X
not_null_assertions	materialize_materialized_view	List of Strings	X
start_offset	materialize_source_kafka	List of Strings
header	materialize_source_kafka	List of Strings
subsource	materialize_source_kafka	List of Objects
subsource	materialize_source_load_generator	List of Objects
schema	materialize_source_postgres	List of Strings
text_columns	materialize_source_postgres	List of Strings	X
subsource	materialize_source_postgres	List of Objects
subsource	materialize_webhook	List of Objects

Blocks We had decided should be singular. There are some blocks that use plural

Attribute	Resource	Type	Plural
auction_options	materialize_source_load_generator	Block	X
counter_options	materialize_source_load_generator	Block	X
marketing_options	materialize_source_load_generator	Block	X
tpch_options	materialize_source_load_generator	Block	X
check_options	materialize_webhook	Block	X
row_properties	materialize_type	Block	X
map_properties	materialize_type	Block	X
list_properties	materialize_type	Block	X

[dehume]

We rename schema as an allowable attribute in the Postgres source #421