Flash Unite and HDA Flowsheet Tutorial Revisions to reflect changes to initialization and scaling updates as well as some overall improvements

[tannerpolley]

For the Flash Unit Model tutorial, changes include:

• Update to initialization
• Added scaling features for some variables
• Revised some language
• Improved overall structure and flow
• • Many other small changes

For the HDA Flowsheet Tutorial, changed include:

• Added Feed and Product unit models to improve the readability of the stream reports and align with current flowsheet standards
• Added full manual flowsheet initialization tutorial
• Added a AutoScaler method for a basic scaling step
• Revised overall structure and readability of many sections
• Many other small changes

---

📚 Documentation preview 📚: https://idaes-examples--143.org.readthedocs.build/en/143/

[bpaul4]

Requested changes offline

[dallan-keylogic]

Can you close this PR and reopen it from a branch on your fork not named "main"? I believe that's one of the things the LBNL folks want us to do.

[ksbeattie]

Replaced by #144