Capture comments in the Risor AST

[myzie]

Discussed in #195

^{Originally posted by alexaandru February 28, 2024}
At a quick glance I could not find them in there, which makes sense, the VM doesn't need them.

However, the AST would also be very valuable for writing a tool for auto formatting, and currently, such a tool would lose the comments information, which obviously would be unacceptable.