fix inverted boolean to number conversion in InfoSetUtil.doubleValue

[SABITHSAHEB]

1. InfoSetUtil.doubleValue maps a Boolean with the two constants reversed: true returns 0.0 and false returns 1.0, the opposite of XPath 1.0 (boolean true converts to 1, false to 0) and of number() directly below it and BasicTypeConverter, which both map true to 1 and false to 0.
2. doubleValue is the numeric coercion behind the arithmetic operators, the relational operators (<, >, <=, >=), floor/ceiling/round and the substring index arguments, so any comparison or arithmetic that coerces a boolean-valued node or variable is evaluated with the operand negated; a predicate such as node[flag > 0] then selects the wrong set of nodes on caller-supplied data, while number($flag) on the same value returns the correct result.

Swapped the two constants so doubleValue agrees with number() and the spec. Added a CoreFunctionTest case over the doubleValue path (arithmetic, relational, floor/ceiling/round) that fails before the change and passes after.

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