JS: Support TypeScript 5.9 and support 'import defer' syntax

[asgerf]

• Upgrades the bundled TypeScript compiler to version 5.9.
• Adds support for the new import defer syntax mentioned in the TypeScript 5.9 changelog
• Adds import defer parsing support in our JavaScript parser, as this is also a stage 3 JS feature.
• The presence of the defer keyword can be checked in QL with ImportDeclaration.isDeferredImport(). This feature doesn't really affect our analysis so we don't currently use it for anything.