Add support for capitalized month names when casting dates

## Background
Currently, the pattern `ddMMMyyyy` doesn't work for dates like `11JAN2026`, only `11Sep2012`.

In Java this is fixed by making the formatter case-insensitive:
```scala
val formatter = new DateTimeFormatterBuilder()
.parseCaseInsensitive()
.appendPattern("ddMMMyyyy")
.toFormatter(Locale.ENGLISH);
```

However, Spark does not do that and patterns are case sensitive.

## Feature
Add support for capitalized month names when casting dates.

## Business Value
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## Example [Optional]
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## Proposed Solution [Optional]
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