Pass in the type as a string

[Fokko]

Feature Request / Improvement

Right now we expect to pass in the actual string:

schema = Schema(
    NestedField(1, 'foo', StringType())
)

I think it would be nice to also allow strings:

schema = Schema(
    NestedField(1, 'foo', 'string')
)

At the same time, we should reject complex types (list/map/struct).

[kevinjqliu]

'string' here should match the literal in the PrimitiveType

iceberg-python/pyiceberg/types.py

Line 765 in 778db75

root: Literal["string"] = Field(default="string")

[sunxiaojian]

@Fokko I made an attempt to submit a PR.