[DEV-9671] expose transformer kva ratings

[Lax125]

Description

Exposes transformer kVA ratings (normal and emergency) to be used in outputting thermal results for transformers in asset-level thermal summary table.

Associated tasks

Tasks this is blocking:

• https://github.com/zepben/opendss-model-processor/pull/198

Test Steps

With the downstream change, Run a work package and ensure that the asset-level thermal results for transformer have the correct normal and emergency kVA ratings.

Checklist

If any of these are not applicable, strikethrough the line ~like this~. Do not delete it!. Let the reviewer decide if you should have done it.

Code

• I have performed a self review of my own code (including checking issues raised when creating the PR).
  - [ ] I have added/updated unit tests for these changes, and if not I have explained why they are not necessary.
  - [ ] I have commented my code in any hard-to-understand or hacky areas.
• I have handled all new warnings generated by the compiler or IDE.
• I have rebased onto the target branch (usually main).

Security

When developing applications, use following guidelines for information security considerations:

• Access to applications should be protected with security keys/tokens or usernames and passwords;
• All sessions are encrypted if possible;
• All application input is sanitised before being acted on (ie SQL statements, etc);
• Log messages, and especially client-facing ones, must be handled securely and must not leak credentials information (internal URLs, passwords, tokens).

• I have considered if this change impacts information security and made sure those impacts are handled.

Documentation

• I have updated the changelog.
  - [ ] I have updated any documentation required for these changes.

Breaking Changes

• I have considered if this is a breaking change and will communicate it with other team members by posting it on the Slack breaking-changes channel.

No breaking changes.