[CodingStyle] Deprecate EncapsedStringsToSprintfRector

[TomasVotruba]

Deprecate EncapsedStringsToSprintfRector.

Turning string interpolation into sprintf()/concat is a personal preference, not a correctness or upgrade change. On top of that, the rule output is ambiguous - the same input produces a different result depending on the value type and the always configuration:

-echo "Unsupported format {$format} - use another";
+echo sprintf('Unsupported format %s - use another', $format);

-echo "Try {$allowed}";
+echo 'Try ' . $allowed;

Same input, two different output styles - one sprintf(), one concat. With always: true the second one becomes sprintf() too. Hard to predict, and the "more readable" claim goes both ways.

Rule is kept as a deprecated no-op that throws when used, and removed from the CodingStyle level.