Add support for snitch's defmethod

[mathieuroblin]

Description

This MR adds support for the defmethod* macro in all existing snitch commands, namely:

{
  "command": "cpt.snitch.instrumentTopLevelForm",
  "category": "[CPT] Snitch",
  "title": "Instrument Top Level defn/defmethod/let/fn"
},
{
  "command": "cpt.snitch.instrumentCurrentForm",
  "category": "[CPT] Snitch",
  "title": "Instrument Current Form defn/defmethod/let/fn"
},
{
  "command": "cpt.snitch.getSnitchedDefnResults",
  "category": "[CPT] Snitch",
  "title": "Get Snitched defn/defmethod Results"
},
{
  "command": "cpt.snitch.reconstructLastDefnCallToClipboard",
  "category": "[CPT] Snitch",
  "title": "Reconstruct Last defn/defmethod Call to Clipboard"
},

Closes #31

Since there is no tests for this, I am attaching a video for both clj/cljs

defmethod_clj.mov

defmethod_cljs.mov

Checklist

• I have read CONTRIBUTING.md
• There is an issue with a clear problem statement related to this change
• I have added an entry to the [Unreleased] section of CHANGELOG.md linking to the issue(s) addressed
• README/docs updated (or not relevant)
• My changes generate no new warnings
• New and existing unit tests pass locally with my changes

[PEZ]

Thanks! 🙏