Missing Pkl Type Implementations

[z-jxy]

There's a few pkl types that haven't been implemented. I think most of these could be represented by the type system or creating a struct for them. Will also need to add deserializers for these types

• DURATION => std::time::Duration
• DATA_SIZE => rpkl::value::DataSize
• PAIR => tuple with 2 elements
  • This causes PklValue to have infinite size (fixed by storing in a Box)
• INT_SEQ => std::ops::Range<i64>
• REGEX => added Regex(String) variant to PklValue/Value
TYPE_ALIAS => doesn't appear in the evaluated module response, so this can be ignored

These should be added as variants to PklValue.