Provides helpers to access information about the execution environment

[cderv]

1.8.19 exposes the information as a JSON file in QUARTO_EXECUTE_INFO:

• add execute information to all engines in environment quarto-cli#13171

This package should offer helpers to access some of the information in there, as this is a lot !

• Format information: communicate format output to all engines  quarto-cli#2216
• Language information
• pdf-engine used: Quarto equivalent to `rmarkdown::metadata`? quarto-cli#13371