fix(execute): parse stringified objects

[glowcloud]

Refs swagger-api/swagger-ui#7734

This example from the test:

requestBody: {
  a: {
    b: 'c',
    c: ['d', 'e'],
    d: {
      e: 'f',
    },
  },
},

will return:

a%5Bb%5D=c&a%5Bc%5D=%5B%22d%22%2C%22e%22%5D&a%5Bd%5D=%7B%22e%22%3A%22f%22%7D

which should decode to:

a[b]=c&a[c]=["d","e"]&a[d]={"e":"f"}

As established for previous issues, we're not encoding nested objects/arrays, as the behaviour for that is undefined.

[swagger-bot]

🎉 This PR is included in version 3.27.1 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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