Standardize which links open in a new tab on our `hyp3-docs` website

[jtherrmann]

Jira: https://asfdaac.atlassian.net/browse/TOOL-2698

Note: The above link is accessible only to members of ASF.

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Currently we're not consistent about when to use target=_blank, so we should pick one approach and update all of our pages to follow it.