lua,meta - resolve int keys as ints

[cscheid]

Closes #8086.

This "resolves" the issue by allowing meta arrays to be indexed. The syntax is a bit clunky, but the regression test includes a minimal example:

---
title: issue-8086
testkey:
  - "value 1"
  - "value 2"
testkey2:
  testkey: testvalue
_quarto:
  tests:
    html:
      ensureFileRegexMatches:
        - 
          - "testvalue"
          - "value 1"
---

{{< meta testkey.1 >}}

{{< meta testkey2.testkey >}}