Assorted minor tasks

[lemmih]

Issue summary

• forest-cli archive export doesn't warn before overwriting the output-path. We should prompt if the output path already exist and there should be a --force flag to suppress the prompt.
• forest-cli archive export uses --output-path but forest-cli snapshot export uses just -o and forest-cli snapshot compress uses --output. We should be consistent and always use the same flag name.
• Rename forest-cli db clean to db destroy.

Other information and links

[jdjaustin]

Third task completed in PR #3355