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