[6.x] Add png output to reports 65 (#24759)

[stacey-gammon]

• Changes for new PNG image output for reports

Change PNG button name from Download to Generate

Changes for new PNG image output for reports

Change PNG button name from Download to Generate

Remove compatabilityShim from PNG and move to PDF folders

Changed API parameters to contain only required parameters

Added test cases for PNG reporting and added title back into the PNG API call

Merge of security changes for PNG reporting

Fixed issues with test cases for both PDF and PNG

Updated test snapshots for PNG and PDF test changes

• Adding new security changes made for PDF into new PNG code

• Removed commented out lines that were not needed

Summary

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Checklist

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• This was checked for cross-browser compatibility, including a check against IE11
• Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
• Documentation was added for features that require explanation or tutorials
• Unit or functional tests were updated or added to match the most common scenarios
• This was checked for keyboard-only and screenreader accessibility

For maintainers

• This was checked for breaking API changes and was labeled appropriately
• This includes a feature addition or change that requires a release note and was labeled appropriately

[elasticmachine]

💔 Build Failed

• continuous-integration/kibana-ci/pull-request

[elasticmachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request