Implement modulo operator for MONEY/SMALLMONEY types

[hopebo]

Description

Due to the missing modulo operator for MONEY/SMALLMONEY types, it will choose the other Postgres internal alternatives like int4mod and numeric_mod, which will involve additional implicit CASTing between MONEY/SMALLMONEY types and other types. These CASTings could cause loss of precision and wrong results. What's more, the result of calculation won't be MONEY/SMALLMONEY types any more.

Fix

Implement the modulo function and operator for MONEY/SMALLMONEY types. The reason why we don't need to implement the functions between MONEY/SMALLMONEY types and interger types is that it will choose the MONEY-MONEY/SMALLMONEY-SMALLMONEY functions to calculate. And the result type is expected.

Task: BABEL-5480

Check List

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[coveralls]

Pull Request Test Coverage Report for Build 12757649408

Details

• 8 of 9 (88.89%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.006%) to 74.963%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
contrib/babelfishpg_money/fixeddecimal.c	8	9	88.89%

Totals
Change from base Build 12742860948:	0.006%
Covered Lines:	46988
Relevant Lines:	62682

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💛 - Coveralls

[Deepesh125]

there could be user defined objects depend on this. so lets create try..catch.. block where we only create operator if it does not exist.

DO $$
BEGIN
IF NOT EXISTS(SELECT 1 FROM pg_catalog.pg_operator WHERE oprleft = 'numeric'::pg_catalog.regtype and oprright = 'int4'::pg_catalog.regtype and oprnamespace = 'sys'::regnamespace and oprname = '<' and oprresult != 0) THEN
CREATE OPERATOR sys.< (
    LEFTARG = numeric,
    RIGHTARG = int4,
    FUNCTION = sys.numeric_int4_lt,
    COMMUTATOR = >,
    NEGATOR = >=,
    RESTRICT = scalarltsel,
    JOIN = scalarltjoinsel
);
END IF;
END $$;

[Deepesh125]

we should have upgrade test cases, prepare/verify/cleanup format