Fix JSON Read Issues for URDB Downloads

[cpaulgilman]

Pull Request Template

Description

Use IsNumber() in place of IsDouble() to check numeric values from URDB JSON because tier max values are stored as integers, not doubles.

Use UTF16 instead of UTF8 to fix problem reading some URDB JSON in Windows.

Add RapidJSON error codes to error messages to help with future troubleshooting.

Fixes #1848

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
• This change modifies variables in existing compute modules. Please see Checking for PySAM Incompatible API Changes.

Checklist:

If you have added a new compute module in a SSC pull request related to this one, be sure to check the Process Requirements.

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have checked my code and corrected any misspellings

[sjanzou]

Thanks for finding and fixing the issues!