fix: create a copy for CODAP v3

[kswenson]

In #354, the CloudContent.getClientContent() function was changed from:

  getClientContent() {
    return this.content.content ?? this.content
  }

to

  getClientContent() {
    return CloudContent.wrapFileContent
            ? this.content.content
            : this.content
  }

under the mistaken assumption that the CloudContent.wrapFileContent setting was a reliable indicator of whether the content in question was wrapped in CFM metadata or not. It turns out that the content is always wrapped internally by the CFM--the CloudContent.wrapFileContent setting merely determines whether it should be saved to file/disk in its wrapped or unwrapped form. The problem with the original form of the test is that some clients, e.g. CODAP v3, have an internal content property which results in getClientContent() returning the interior content in error. The proper fix from this PR is:

  getClientContent() {
    // if we can specifically identify client content, then return it
    if (CloudContent.isClientContent(this.content?.content)) return this.content.content
    if (CloudContent.isClientContent(this.content)) return this.content
    // otherwise, assume that a nested `content` property means we are wrapped
    return this.content?.content
            ? this.content.content
            : this.content
  }

The rest of the changes in this PR are additional comments, tests, and minor refactoring to make all of this a bit clearer.

[eireland]

👍 LGTM