feat: add metadata updates and requirements interface

[gty404]

This commit introduces the metadata update and update requirements system for table metadata modifications.

[zhjwpku]

I was initially confused about renaming MetadataUpdate to TableUpdate and UpdateRequirement to TableRequirement, but after checking the iceberg-rust and iceberg-python implementations, it now makes sense to me.

[wgtmac]

While I know both iceberg-python and iceberg-rust name them as TableUpdate and TableRequirement. However, it might looks weird to use Table prefix in terms of dealing with updates to table, view and perhaps the in-discussion materialized view.

WDYT? @Fokko @liurenjie1024

[liurenjie1024]

While I know both iceberg-python and iceberg-rust name them as TableUpdate and TableRequirement. However, it might looks weird to use Table prefix in terms of dealing with updates to table, view and perhaps the in-discussion materialized view.

WDYT? @Fokko @liurenjie1024

Thanks @wgtmac for pinging me. I prefer to add an prefix to improve readability.

[wgtmac]

Generally looks good. I left some minor comments.

[wgtmac]

Thanks @liurenjie1024 for the input! I think we should stick with the rest catalog api to use TableUpdate, ViewUpdate, etc.

[wgtmac]

LGTM. I've just left a comment w.r.t. class names.