[BUGFIX] Fixed current extensionscope for fetching viewconfiguration

FluxService::getViewConfigurationForExtensionName() should fetch
TypoScriptSubConfiguration using the extension key, not extension
names like "Vendor.ExtName"
Merge pull request #598 from higidi/bugfix/extensionscope-for-fetching-viewconfiguration

[BUGFIX] Fixed current extensionscope for fetching viewconfiguration
[TASK] Accomodate 6.3 branches in unit test
[BUGFIX] Ensure argument types in BackendConfigurationManager

Also implemented an intermediate variable to avoid a repeated function call.

Close: #596
[TASK] Compact a loop expression in BackendConfigurationManager

Switch foreach() to single line while().
[TASK] Yoda CGL
[FEATURE] Allow using full qualified ll ala LLL:path:key for form components
[TASK] Refactored if condition resolving LLL refs of form components
[TASK] Implement own method building default view configuration for ext key

Implement an own method building the default view configuration of the
given extension key, so it can be better extended by sub-services like
fluidpages or fluidcontent, which can provide by default a deeper folder
structure. (e.g "Templates/Page" for fluidpages or "Templates/Content"
for fluidcontent).
[TASK] Make method building the default viewconfiguration protected
[FEATURE] Expose getter and setter for page UID in BackendConfigurationManager

Allows consumers to override the page UID that gets used in *every* backend operation. Use with great care and be sure to also use the backup and restore methods!
[TASK] CGL fix for inline control structure
Merge pull request #599 from higidi/feature/implement-own-method-for-building-default-viewconfiguration

[TASK] Implement own method building default view configuration for ext key
Merge pull request #601 from higidi/feature/allow-using-full-qualified-ll-for-form-component-labels

[FEATURE] Allow using full qualified ll ala LLL:path:key for form components
[TASK] Change a bodiless control structure to one with body
[TASK] Add a preparedGet method on RecordService

This method should allow us to easier implement workspace awareness through this single contact point.
[TASK] Start overlaying records fetched via WorkspacesAwareRecordService
[TASK] Wrap and short-circuit workspace overlay if not installed
[TASK] Improve workspaces enabled check and overlaying
[BUGFIX] Correct expectation for check of return from RecordService