fix(appconfig): format app values

[ArtificialOwl]

returns formated values based on type when calling getAllValues() and searchValues()

note: deprecated method getValues() use getAllValues() but if the config value is defined as MIXED (default), the value is kept as a string.

original:

{
"key1": "value1",
"key2": "value0",
"key6": "1",
"key7": "{\"test1\":1,\"test2\":2}",
"test8": "1",
"key3": "value0",
"key4": "3",
"key5": "3.14"
}

new:

{
"key1": "value1",
"key2": "value0",
"key6": true,
"key7": {
"test1": 1,
"test2": 2
},
"test8": true,
"key3": "value0",
"key4": 3,
"key5": 3.14
}

same as #43258 with tests

[ArtificialOwl]

/backport to stable29