[Java/C++] Archive variable length recordings.

[vyazelenko]

This PR changes Archive recordings from being fixed length (1KB) to variable-length.

Summary:

• Recording descriptors are variable-length.
• No limitation on the length of the strippedChannel, originalChannel and sourceIdentity Strings.
• Ability to purge recordings (io.aeron.archive.client.AeronArchive#purgeRecording), i.e. mark recording as INVALID and delete the corresponding segment files.
• max-entries commands in ArchiveTool have been deprecated in favor of capacity, i.e. Catalog no longer has a max entries limit but has a capacity expressed in bytes. Catalog is auto-growing it's capacity when needed but an explicit command can be used as well.
• New command ArchiveTool#compact to compact the Catalog file, i.e. remove all recordings in state INVALID and delete the corresponding segment files.
• Add checksum to the RecordingDescriptorHeader. Now if the io.aeron.archive.Archive.Context#recordChecksum() is set the checksum of the entire RecordingDescriptor will be taken and stored in the header.
• ArchiveTool#verify - validate RecordingDescriptor checksums.
• ArchiveTool#checksum - compute and persist RecordingDescriptor checksums.
• Add support for jumbo RecordingDescriptors, i.e. allow RecordingDescriptors bigger than the tryClaim size by using Publication#offer API.
• Migration task to migrate from version 2 to version 3 of the Archive.