lami: bug 510984: allocate new formatter for each axis

lami: bug 510984: allocate new formatter for each axis

When two axis show the same data type both have
the same formatter with the Y-axis internal and external ranges.

Allocate a new formatter each time with the corresponding internal and
external ranges.

Formatters are now immutable.

Change-Id: If01d5cb4f9a396fa37fad8295ad2a41cc6401e3c
Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Reviewed-on: https://git.eclipse.org/r/89465
Reviewed-by: Genevieve Bastien <gbastien+lttng@versatic.net>
Tested-by: Genevieve Bastien <gbastien+lttng@versatic.net>
Reviewed-by: Hudson CI