Interstitial tag support Mamba 2.0

[rmigneco]

Description

This PR adds support for Interstitial Tag Attributes as outlined in the Appendix D of the HLS Spec

Note - this is a port of the work from #144 but updated for Mamba 2.0 syntax

Change Notes

• Adds PantosValue attributes to support interstitials
• Updates the EXT_X_DATERANGETagValidator to include additional values and include specific validation rules for HLS Interstitials
• Adds unit tests for the new validation rules
• Creates HLSInterstitialValues to represent the attribute options
• Creates InterstitialTagBuilder which facilitates creating a HLSTag type configured specifically for interstitials
• Unit tests for InterstitialTagBuilder

Pre-submission Checklist

• I ran the unit tests locally before checking in.
• I made sure there were no compiler warnings before checking in.
• I have written useful documentation for all public code.
• I have written unit tests for this new feature.