Adjust prerequisite content in the installation section

[MikeBauerCA]

Proposed changes

This PR removes the "Installing Prerequisites" section from the installation of VS Code and extensions chapter. Node.js is only a prerequisite for Zowe CLI so that content has been moved to the Zowe CLI installation section. The Java SDK was only required for Z Open Editor so the content now refers the reader to the prerequisite information shown on the VS Code marketplace for that extension at https://marketplace.visualstudio.com/items?itemName=IBM.zopeneditor#prerequisites

Also in this PR is a small change to the Front_Matter.tex files to render images appropriately in the generated PDFs.

Type of change

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• Bug fix (change which fixes one or more issues)
• New feature (change which adds functionality or features to the course)
• Translations (change which adds or modifies translations of the course)
• Documentation (change which modifies documentation related to the course)
• This change requires an update to the course's z/OS environment

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• I have read the Contributing Guideline
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• I have DCO-signed all of my commits that are included in this PR
• I have tested it manually and there are no regressions found
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• I have made corresponding changes to the documentation (if appropriate)

[tanto259]

Looks good to me. Thanks, Mike!

[MikeBauerCA]

Thank you, I'm going to proceed with the merge. For any additional changes prior to the upcoming release, we can create a new branch.