perlin-noise: fix racy initialization

Fixing issue #160, by initializing the tables used by perlin noise during
class_init of the GeglOperation using it. There is much room for optimization
by refactoring the gegl-op to directly include inlined versions of the code
currenly in the perlin folder.
parent 0b8a4082
Pipeline #83883 failed with stages
in 7 minutes and 57 seconds