make VisiumHD vignettes

[alikhuseynov]

use the existing standard Visium vignettes (both .Rmd and .ipynb) as framework to make new VisiumHD vignettes.
all commits to documentation-devel branch.
Example to load VisiumHD using SFE commit 748f6fd or devel branch

# path to "binned_outputs" directory containing:
└── binned_outputs
    ├── square_002um
    ├── square_008um
    └── square_016um
dir_hd <- "~/Downloads/Visium_HD_Mouse_Brain/binned_outputs/"
# public dataset -> https://www.10xgenomics.com/datasets/visium-hd-cytassist-gene-expression-libraries-of-mouse-brain-he
sfe_hd <-
  read10xVisiumSFE(samples = list.files(dir_hd), # 1:3 resolutions
                   dirs = dir_hd,
                   bin_size = c("8", "16"), # this defines which of 1:3 resolutions to load
                   type = "HDF5", # Note, "sparse" takes longer to load
                   data = "filtered", # spots under tissue
                   images = c("lowres"), # for now low res. image only
                   add_Graph = FALSE # Note, this can take time for VisiumHD for 2 or 8µm res.
                   )
sfe_hd