Add validation to ensure that settings.configs values are dictionaries, in order to prevent misuse (#1547)

* Add validation to ensure settings.configs values are dictionaries to prevent misuse

* Add tests for invalid settings.configs value formats

* Replaced with filter and split into a function

* Rename invalidConfigsFormat to invalidConfigsMappingFormat

* Add comments to explain invalid  fixture

* Rename test fixture

* Update CHANGELOG.md

* Correct grammer

* Use KeyPath instead of closure

* Rename validateMappingStyleInConfig to extractValidConfigs

* Add a document comment for extractValidConfigs(from:)

* Use old testing api and remove EquatableErrorBox

* Rename test case to use "mapping" instead of "dictionary"

* Add ValidSettingsExtractor to encapsulate the logic for converting a dictionary to Settings

* Add settings validation for both Target and AggregateTarget

* Add tests for invalid settings.configs in Target and AggregateTarget

* Add document comments for ValidSettingsExtractor

* Rename ValidSettingsExtractor to BuildSettingsExtractor

* Add settings validation for settingGroups

* Add tests for settingGroups

* Rename extract to parse

* Refactor

* Update Tests/ProjectSpecTests/InvalidConfigsFormatTests.swift

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Co-authored-by: Yonas Kolb <yonaskolb@users.noreply.github.com>