Proposed changes

I've encountered two small typos:

• The CMake release variable was spelled QMCAPCK instead of QMCPACK
  • This doesn't seem to be set anywhere though
• The hdf5 create ignores flags input
  • any created archive would be done with H5F_ACC_TRUNC mode only
  • There are only a few instances of the alternative H5F_ACC_EXCL being used

  AFQMC/Wavefunctions/WavefunctionFactory.cpp
  1191:        if (!restart.create(restart_file, H5F_ACC_EXCL))
  
  AFQMC/Walkers/tests/test_sharedwset.cpp
  252:  if (!dump.create("dummy_walkers.h5", H5F_ACC_EXCL))
  317:  if (!dump.create("dummy_walkers.h5", H5F_ACC_EXCL))
  458:    if (!dump.create("dummy_walkers.h5", H5F_ACC_EXCL))
  

What type(s) of changes does this code introduce?

• Bugfix
• Code style update (formatting, renaming)

Does this introduce a breaking change?

• No

What systems has this change been tested on?

Checklist

• Yes. This PR is up to date with current the current state of 'develop'
• Yes. Code added or changed in the PR has been clang-formatted
• No. This PR adds tests to cover any new code, or to catch a bug that is being fixed
• No. Documentation has been added (if appropriate)