Enable AMR regression tests

The AMR regression tests are currently disabled.

created branch 95-enable-amr-regression-tests to address this issue

I think these regression tests should be enabled to ensure active maintenance of the AMR solver. Since @frey_m is not actively working on the code, we should make sure that any changes do not affect the functionality of AMR. Currently, there are some issues since string variables are taken from predefined values, so the regression tests input files must be updated. This is giving problems to some users (see thread "simulation with amr fieldsolver" in opal mail list)

The attribute AMR_MG_NORM has to be updated in some input files (see src!491 (comment 33090))

mentioned in issue src#714 (closed)

mentioned in merge request !36 (closed)

created merge request !37 (merged) to address this issue

mentioned in merge request !37 (merged)

mentioned in issue NightlyBuild#32 (closed)

marked this issue as related to NightlyBuild#32 (closed)

mentioned in commit 2bd1995c

closed with merge request !37 (merged)

mentioned in issue #110 (closed)

marked this issue as related to #110 (closed)

marked this issue as related to #78 (closed)