Fix complex log1p accuracy with large abs values. (#88260)

This ports https://github.com/openxla/xla/pull/10503 by @pearu. The new
implementation matches mpmath's results for most inputs, see caveats in
the linked pull request. In addition to the filecheck test here, the
accuracy was tested with XLA's complex_unary_op_test and its MLIR
emitters.