[BUG] [Ada] Server skeleton does not compile when an operation has no parameter

[stcarrez]

• add missing 'use Swagger.Streams;' clause
• add Style_Checks pragma to fix style compilation warnings in generated Ada code
• fix spurious spaces in licence headers that cause Ada style compilation warning
• update the default GNAT project config

Fix #8640

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[wing328]

CircleCI failure not related to this change.