Improve API for the NGFF module

[ziw-liu]

• Repurpose the nomenclature from our dependencies:

• Accessing the 5D arrays (zarr arrays) via position['key'] syntax is not intuitive. Let's implement position.data (set or get property) syntax, which mimics napari's syntax. Add shorthand to get raw data in NGFF positions #61

• Rename the ImageArray object to ZarrArray to make it obvious that the object is a zarr array. Should ngff.ImageArray have a different name? #60

• Make it intuitive to read and write tiled acquisitions: Make it easier to write and read tiled dataset. #59

• Introduce a tiles or tiled layout. I picked these words in favor of multiPos or multiFOV. But, I think either of them is a decent choice.

• Make it intuitive to over-write channels: Method to delete or rename channel in NGFF datasets #56 Get NGFF channel index from name #70

• setitem (position[array_name][:, channel_index] = array) is too complex a usage, let's provide a wrapper delete_channel or overwrite_channel. delete_channel is more broadly useful.

Originally posted by @mattersoflight in #31 (review)