Remove hardcoded dependency on deno.json

[vwkd]

Currently, fresh has a hardcoded dependency on ./deno.json for compiler options and throws and error if it doesn’t exist.

This prevents using fresh in a subdirectory, e.g. src/, of the repository, without maintaining duplicate deno.json files.

Workaround using a soft or hard link are not optimal. Also they introduce more issues, e.g. a soft link is currently not recognized by vscode_deno extension which prevents IntelliSense denoland/vscode_deno#784, while a hard link is not recognized by git which makes it impossible to synchronize it across different computers.

It would be great if the hardcoded dependency on ./deno.json could be avoided, made optional or configurable.

Seems to be introduced in #610 (review)

[lucacasonato]

We should walk up the tree to find the deno.json that is in use.

[iuioiua]

I think there are better alternatives, such as providing a CLI flag or taking advantage of Deno's inbuilt method of finding the deno.json, which would only be made possible by a new function in the runtime API (proposal here).