cargo-pgx schema to stdout by default

[Hoverbear]

This solves the same problem described in #437 but instead of changing the name, we have adapted the behavior of cargo pgx schema to default to stdout, as there is no real 'default' since many extensions don't use sql/ at all.

This was described in detail in #437 (comment)

ana@autonoma:~/git/zombodb/pgx/pgx-examples/arrays$ cargo pgx schema > out.sql
    Building for SQL generation with features ``
    Finished dev [unoptimized + debuginfo] target(s) in 0.08s
 Discovering SQL entities
  Discovered 14 SQL entities: 0 schemas (0 unique), 13 functions, 1 types, 0 enums, 0 sqls, 0 ords, 0 hashes, 0 aggregates
     Writing SQL entities to /dev/stdout

Outputs

/* 
This file is auto generated by pgx.

The ordering of items is not stable, it is driven by a dependency graph.
*/

-- pgx-examples/arrays/src/lib.rs:32
-- arrays::default_array
CREATE OR REPLACE FUNCTION arrays."default_array"() RETURNS integer[] /* alloc::vec::Vec<i32> */
STRICT
LANGUAGE c /* Rust */
AS 'MODULE_PATHNAME', 'default_array_wrapper';

-- pgx-examples/arrays/src/lib.rs:37
-- arrays::sum_array
-- requires:
--   default_array
CREATE OR REPLACE FUNCTION arrays."sum_array"(
	"input" integer[] DEFAULT default_array() /* pgx::datum::array::Array<i32> */
) RETURNS bigint /* i64 */
 STRICT
LANGUAGE c /* Rust */
AS 'MODULE_PATHNAME', 'sum_array_wrapper';

-- pgx-examples/arrays/src/lib.rs:86
-- arrays::strip_nulls
CREATE OR REPLACE FUNCTION arrays."strip_nulls"(
	"input" integer[] /* alloc::vec::Vec<core::option::Option<i32>> */
) RETURNS integer[] /* alloc::vec::Vec<i32> */
STRICT
LANGUAGE c /* Rust */
AS 'MODULE_PATHNAME', 'strip_nulls_wrapper';

-- pgx-examples/arrays/src/lib.rs:81
-- arrays::i32_array_with_nulls
CREATE OR REPLACE FUNCTION arrays."i32_array_with_nulls"() RETURNS integer[] /* alloc::vec::Vec<core::option::Option<i32>> */
STRICT
LANGUAGE c /* Rust */
AS 'MODULE_PATHNAME', 'i32_array_with_nulls_wrapper';

-- pgx-examples/arrays/src/lib.rs:9
-- arrays::sq_euclid_pgx
CREATE OR REPLACE FUNCTION arrays."sq_euclid_pgx"(
	"a" real[], /* pgx::datum::array::Array<f32> */
	"b" real[] /* pgx::datum::array::Array<f32> */
) RETURNS real /* f32 */
STRICT
LANGUAGE c /* Rust */
AS 'MODULE_PATHNAME', 'sq_euclid_pgx_wrapper';

-- pgx-examples/arrays/src/lib.rs:76
-- arrays::i32_array_no_nulls
CREATE OR REPLACE FUNCTION arrays."i32_array_no_nulls"() RETURNS integer[] /* alloc::vec::Vec<i32> */
STRICT
LANGUAGE c /* Rust */
AS 'MODULE_PATHNAME', 'i32_array_no_nulls_wrapper';

-- pgx-examples/arrays/src/lib.rs:66
-- arrays::static_names_set
CREATE OR REPLACE FUNCTION arrays."static_names_set"() RETURNS SETOF text[] /* alloc::vec::Vec<core::option::Option<&str>> */
STRICT
LANGUAGE c /* Rust */
AS 'MODULE_PATHNAME', 'static_names_set_wrapper';

-- pgx-examples/arrays/src/lib.rs:61
-- arrays::static_names
CREATE OR REPLACE FUNCTION arrays."static_names"() RETURNS text[] /* alloc::vec::Vec<core::option::Option<&str>> */
STRICT
LANGUAGE c /* Rust */
AS 'MODULE_PATHNAME', 'static_names_wrapper';

-- pgx-examples/arrays/src/lib.rs:48
-- arrays::sum_vec
CREATE OR REPLACE FUNCTION arrays."sum_vec"(
	"input" integer[] /* alloc::vec::Vec<core::option::Option<i32>> */
) RETURNS bigint /* i64 */
STRICT
LANGUAGE c /* Rust */
AS 'MODULE_PATHNAME', 'sum_vec_wrapper';

-- pgx-examples/arrays/src/lib.rs:18
-- arrays::approx_distance_pgx
CREATE OR REPLACE FUNCTION arrays."approx_distance_pgx"(
	"compressed" bigint[], /* pgx::datum::array::Array<i64> */
	"distances" double precision[] /* pgx::datum::array::Array<f64> */
) RETURNS double precision /* f64 */
IMMUTABLE PARALLEL SAFE STRICT
LANGUAGE c /* Rust */
AS 'MODULE_PATHNAME', 'approx_distance_pgx_wrapper';

-- pgx-examples/arrays/src/lib.rs:95
-- arrays::SomeStruct
CREATE TYPE arrays.SomeStruct;

-- pgx-examples/arrays/src/lib.rs:95
-- arrays::somestruct_in
CREATE OR REPLACE FUNCTION arrays."somestruct_in"(
	"input" cstring /* &cstr_core::CStr */
) RETURNS arrays.SomeStruct /* arrays::SomeStruct */
IMMUTABLE PARALLEL SAFE STRICT
LANGUAGE c /* Rust */
AS 'MODULE_PATHNAME', 'somestruct_in_wrapper';

-- pgx-examples/arrays/src/lib.rs:95
-- arrays::somestruct_out
CREATE OR REPLACE FUNCTION arrays."somestruct_out"(
	"input" arrays.SomeStruct /* arrays::SomeStruct */
) RETURNS cstring /* &cstr_core::CStr */
IMMUTABLE PARALLEL SAFE STRICT
LANGUAGE c /* Rust */
AS 'MODULE_PATHNAME', 'somestruct_out_wrapper';

-- pgx-examples/arrays/src/lib.rs:95
-- arrays::SomeStruct
CREATE TYPE arrays.SomeStruct (
	INTERNALLENGTH = variable,
	INPUT = arrays.somestruct_in, /* arrays::somestruct_in */
	OUTPUT = arrays.somestruct_out, /* arrays::somestruct_out */
	STORAGE = extended
);

-- pgx-examples/arrays/src/lib.rs:98
-- arrays::return_vec_of_customtype
CREATE OR REPLACE FUNCTION arrays."return_vec_of_customtype"() RETURNS arrays.SomeStruct[] /* alloc::vec::Vec<arrays::SomeStruct> */
STRICT
SET search_path TO @extschema@
LANGUAGE c /* Rust */
AS 'MODULE_PATHNAME', 'return_vec_of_customtype_wrapper';

It also syntax colors to stdout: