timeUnitBandPosition with escaped field (e.g., "\\'fieldName\\'") doesn't work.

[yhoonkim]

Bug Description

When timeUnitBandPosition is set, the escaped field doesn't work.

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "data": {
    "values": [{"'temporal'": "2024-01-01", "group": "x", "value": 0.1}]
  },
  "mark": "bar",
  "encoding": {
    "x": {
      "field": "\\'temporal\\'",
      "type": "temporal",
      "timeUnit": "utcyearmonthdate"
    },
    "y": {"field": "value", "type": "quantitative"}
  },
  "config": {"bar": {"timeUnitBandPosition": 0}}
}

It returns the below error:

Expression parse error: 0.5 * utcOffset('date', datum['utcyearmonthdate_'temporal''], -1) + 0.5 * datum['utcyearmonthdate_'temporal'']

https://vega.github.io/editor/#/url/vega-lite/N4IgJAzgxgFgpgWwIYgFwhgF0wBwqgegIDc4BzJAOjIEtMYBXAI0poHsDp5kTykBaADZ04JAKyUAVhDYA7EABoQAEySYUqUMSSCGcCGgDaoAOSZEONgCcdJtCABMABgcAWfk4CMHz4pBkrNgYcewAPP21dODQnSk8AXwBdeKVkKwBreyYkKz84WSg2ZRpZMjRQcM0QADMaOEFlewAdJrMLax0WuyVMAE8caPRzBEsbQT9MGgQ4AFVZOnsGTCheuByEOXpVcxAUkF7ymrqG+0i9Cf7BkABHBiRZSfVJ0l29wtlasqrs3KrJ6bmdAAQvdlAAFNgQOjseSoJzxBFAA

Checklist

• I checked for duplicate issues.