Add format json option to conan cache path

[juansblanco]

Changelog: Feature: Add --format=json option to conan cache path.
Docs: Omit

Added --format=json option to the conan cache path command that returns a json as:
{"cache_path": "C:\\Users\\user\\.conan2\\p\\zlib2cad50ee1214e\\e"}

Closes: #15599

[jcar87]

LGTM as it is, but I wonder if we might want something slightly more elaborate?

At the moment, the following two invocationS:

conan cache path foo/1.0.0 --format=json

and

conan cache path foo/1.0.0 --folder=metadata --format=json

would both return a json have the key cache_path in the returned json, but pointing to a different folder. This mirrors the behaviour of the regular CLI output, but it makes me wonder if we might want something more "rich"?

e.g.

{
    "cache_path": "C:\\Users\\user\\.conan2\\p\\zlib2cad50ee1214e\\e", 
    "folder": "exports", 
    "reference": "foo/1.0.0"
}

and

   "cache_path": "xxx",
   "folder: "metadata", 
   "reference: "foo/1.0.0"

or even a richer

{
 "ref": "foo/1.0.0#rrev1", 
 "folders": 
     { 
         "exports": "path1",
         "metadata": "path2"
         "export_source": "path3",
         // etc...
      }
}

Just an idea, but perhaps if we decide to do something richer in the future, leave the json today in a way that can be extended without breaking?

[memsharded]

I think it should be good enough with the command to return 1 path only because all the use cases I have found so far it is to do operations on 1 folder, like the metadata one, but it is unlikely to need several folders, and it that is the case they can do several conan cache path calls, not a big issue. So the

{
    "cache_path": "C:\\Users\\user\\.conan2\\p\\zlib2cad50ee1214e\\e", 
    "folder": "exports", 
    "reference": "foo/1.0.0"
}

Should be future-proof enough, and maybe if we want a multiple-paths command and accept multiple --folder arguments, the output format can change anyway to accommodate for that, as this would be an opt-in.

Because for the basic case I am concerned that you'd need to use both the argumetn --folder=xxxx and then yet again the same in the jq query or to parse the json with data["folders"][xxxxx] to get the value you requested as an argument?

So I think might be good as-is

[jcar87]

Makes sense! Merging :) Thanks @juansblanco !!