anndataR 0.99.0

New features

PR #158: Change package version from 0.0.0.9000 --> 0.99.0 to align with Bioc devel versioning standards.
- Update DESCRIPTION file to reflect current release R version used by Bio: R (>= 3.2.0) --> R (>= 4.3.0).
- Reformat NEWS file to follow some conventions.
Various PRs: Initial release of anndataR, providing support for working with AnnData objects in R. Feature list:
- Slots:
  - X
  - layers
  - obs
  - obs_names
  - var
  - var_names
- Backends:
  - HDF5AnnData
  - InMemoryAnnData
- Converters:
  - SingleCellExperiment
  - Seurat