Normalize data types.

[dblodgett-usgs]

From pizzarr:

Data types

Zarr Data Type	Status (reading / writing)	Notes
b1 / boolean	✔ / ✔	Converted to logical in R.
i1 / int8	✔ / ✔	Converted to integer in R.
u1 / uint8	✔ / ✔	Converted to integer in R.
i2 / int16	✔ / ✔	Converted to integer in R.
u2 / uint16	✔ / ✔	Converted to integer in R.
i4 / int32	✔ / ✔	Converted to integer in R.
u4 / uint32	✔ / ✔	Converted to integer in R.
i8 / int64	✔ / ✔	Converted to integer in R.
u8 / uint64	✔ / ✔	Converted to integer in R.
f2 / float16	✔ / ✔	Converted to double in R.
f4 / float32	✔ / ✔	Converted to double in R.
f8 / float64	✔ / ✔	Converted to double in R.
complex	❌ / ❌
timedelta	❌ / ❌
datetime	❌ / ❌
string	✔ / ✔	Converted to character in R.
Unicode	✔ / ✔	Converted to character in R.
void *	❌ / ❌
Structured data types	❌ / ❌
Object data type - VLenUTF8	✔ / ✔	Converted to character in R.

From RNetCDF, numeric are doubles by default but can be coerced to a smaller type according to:

NC_TYPE	R Type
NC_BYTE	integer
NC_UBYTE	integer
NC_SHORT	integer
NC_USHORT	integer
NC_INT	integer
NC_UINT	double
NC_FLOAT	double
NC_DOUBLE	double
NC_INT64	bit64:bit64-package]{integer64
NC_UINT64	bit64:bit64-package]{integer64