Add startsWith predicate

[rdblue]

Some users have requested prefix matching or startsWith.

This issue was migrated from Netflix/iceberg#49.

[rdblue]

The Netflix repository had an incomplete PR that is a good starting point: Netflix/iceberg#78

[renato2099]

Hey @rdblue I just pushed a PR for this issue
#75

[xabriel]

#327 was merged. Should we close this?

[rdblue]

Feel free to close issues like this. It's easy to reopen them if we need to.

[xabriel]

I only have comment privileges :)

[rdblue]

I didn't realize that was locked down. Good to know, thanks!