fix(mysql): change Types const enum to regular enum - #75611

const enums cannot be imported when a consumer enables TypeScript's verbatimModuleSyntax, since the compiler needs the enum's runtime value to inline it and const enums are erased ambiently (TS2748: Cannot access ambient const enums when 'verbatimModuleSyntax' is enabled). Switching to a regular enum keeps the same values/behavior while remaining importable under verbatimModuleSyntax.

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