More common tests

Default engine is BPFile, i.e. as of today, for writing it is always …

Default engine is BPFile, i.e. as of today, for writing it is always a BP3 engine, for reading it is BP3 or BP4 depending on the file it is opening.

* commit 'd93747d5':
  remove debug prints in BP4 serializer
  Fix flake8 errors
  Install all .py files for bp4dbg
  bp4dbg: dump metadata too. Print values for characteristics and attributes. Fix: BP4 and BP3 attribute length in data was written as 8 bytes and the wrong value; now writing the correct length and on 4 bytes only.

Disable install tests until CI issues are resolved

bp4dbg: dump metadata too. Print values for characteristics and attributes. Fix: BP4 and BP3 attribute length in data was written as 8 bytes and the wrong value; now writing the correct length and on 4 bytes only.

Add Install tests

Local array read block bug

remove spurious printf

Add a Null2 engine that operates at the core::Engine level

Improvements to installation documentation.

Bp4 buffer tags and bp4dbg.py tool

Updating count in BP3 and BP4 deserializer
Added test

fixed a few problems in ssc tests

Fix BP4Base::ResizeBuffer() to use vector size() not capacity() just like as it was fixed in BP3Base already

Add a python tool bp4dbg to dump a BP4 dataset. Only for data files yet, not for metadata and index table.

- Add tags to different elements in BP4 Data buffer
  - [PGI...PGI] for PG blocks,
  - [VMD..VMD] for variable metadata, data blocks are outside this tag
  - [AMD..AMD] for attribute metadata, values are inside this tag
- Pad variable metadata blocks so that variable data always starts on aligned position in memory (not on final file offset).
- Do not write dimensions in characteristics in the data buffer since a fixed entry exists for dimensions. In ADIOS 1.x these could be different (variable ID vs actual dimension numbers) but ADIOS2 does not have this anymore.
- Do not write footer (metadata) to the end of data file on close. Metadata only exists in the global md.0 file and inside the data buffers in data.* interspersed witht the data itself (for recovery)
- Bug fix: use BP4Base::ResizeBuffer consistently instead of BufferSTL::Resize because they work differently based on capacity versus size. This fixes the CI test errors.

SST RDMA data plane fixes

Small quality of life improvements to basic examples.