Prevent insertion of script tags if document already contains them

[paulwarren-wk]

If the viewer build was given a file that already contained an iXBRL viewer as input, it would add a second pair of <script> tags, leading to unpredictable results when the viewer was opened.

With this PR, the builder raises an error if given a viewer file as input.

Fixes #293

[aviary2-wf]

Security Insights

(1) Vulnerable direct dependencies were detected

1 vulns in numpy < 1.21 via requirements.txt

Action Items

• Review dependencies for available updates
• See this Splunk dashboard for more CVE details
• Review PR for security impact; comment "security review required" if needed or unsure
• Verify aviary.yaml coverage of security relevant code

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Questions or Comments? Reach out on Slack: #support-infosec.

[derekgengenbacher-wf]

QA +10 Unit and Skynet tests pass successfully. Builds successfully. Successfully verified this by running the viewer once on a document and then running it again and generating the error.

@Workiva/release-management-p

[rmconsole-wf]

+1 from RM