Make regexp pattern [^a] consistent with Spark for multiline strings

[andygrove]

Signed-off-by: Andy Grove andygrove@nvidia.com

Closes #4229

The following documentation from this PR explains the transpiler change that makes us consistent with CPU for patterns such as [^a].

// There are differences between cuDF and Java handling of newlines
// for negative character matches. The expression `[^a]` will match
// `\r` and `\n` in Java but not in cuDF, so we replace `[^a]` with
// `(?:[\r\n]|[^a])`. We also have to take into account whether any
// newline characters are included in the character range.
//
// Examples:
//
// `[^a]`     => `(?:[\r\n]|[^a])`
// `[^a\r]`   => `(?:[\n]|[^a])`
// `[^a\n]`   => `(?:[\r]|[^a])`
// `[^a\r\n]` => `[^a]`

[andygrove]

build

[jlowe]

build