std/jsonc seems to strip comments

**Describe the bug**

esm.sh is currently unable to update an existing deno.jsonc file. See: https://github.com/esm-dev/esm.sh/issues/686.
While implementing, it came to light, that the jsonc parser in the deno std lib seems to discard comments.
(see this issue, comment by farsightsoftware: https://github.com/esm-dev/esm.sh/issues/687)

I've not checked it myself yet, but I asked farsightsoftware to add an example to this issue.

The main usecase for this std lib is currently updating the deno.jsonc file, so it would make it a lot easier for all tools dealing with the deno.jsonc file if it would preserve comments automatically.

**Steps to Reproduce**

TODO

**Expected behavior**

The jsonc parser output is able to be stringified again and produce identical output to the original jsonc input.

In diagram:

jsonc file
=> jsonc parser
=> some intermediate representation
=> jsonc stringifier
=> a file identical to the original jsonc file
(especially with comments)

**Environment**

TODO