[Format] Add LargeBinary and LargeString types

[asfimport]

These are string and binary types that use 64-bit offsets. Java will not need to implement these types for the time being, but they are needed when representing very large datasets in C++

Reporter: Wes McKinney / @wesm
Assignee: Antoine Pitrou / @pitrou

Related issues:

• [Format][C++] Add "LargeList" type with 64-bit offsets (is related to)
• [Python] Expose LargeBinaryType and LargeStringType (is required by)

PRs and other links:

• GitHub Pull Request #4919
• GitHub Pull Request #4921

_{Note: This issue was originally created as ARROW-750. Please see the migration documentation for further details.}

[asfimport]

Antoine Pitrou / @pitrou:
Two questions :

1. what is the process for evolving the memory layout specification?
2. string and binary types are currently not part of the memory layout specification (instead they are assumed to be backed by physical list arrays). Should we do the same for large string / binary types, i.e. add a large list physical type?

[asfimport]

Antoine Pitrou / @pitrou:
Issue resolved by pull request 4921
#4921