The supported compression methods.
The support of the built-in methods is resolved against the compression streams available when
the function is called, i.e. the classes set with configure and the implementations
embedded in the build. A caller can test whether an entry is readable by looking up
EntryMetaData#compressionMethod in the result and checking
EntryMetaData#encrypted; FileEntry#getData remains the authority.
Returns the compression methods supported in the current environment and configuration: the built-in methods followed by the codecs registered with registerCodec, in registration order.