feat: Add support for middlewares

[abichinger]

I originally used the middleware to sanitize the translation keys.
I’ve now done the sanitization directly in the typechat service. (see #280)

I’ll leave this here as a draft for now. Maybe a middleware will be needed in the future.

[fkirc]

Given that unit-tests are currently failing and its status as a draft, I will leave this open for the time being.
Please let me know in case if you are willing to finish it fully and fix the tests.

[abichinger]

Sorry for the noise. The tests are now successful. I would suggest not merging the PR for the time being, because no middleware is currently needed. I would just leave the PR open, in case it’s needed in the future.

If you don’t think middleware makes sense, then you’re also welcome to close this PR.

[fkirc]

Alright, let's keep the PR open until there is a pressing use case for it.
By the way, I would rather suggest to allow custom NodeJS-scripts as middleware, something like --middleware=some_node_script.js.
Then everyone could roll their own middleware without being dependent on me or someone else merging any middleware into the TypeScript-code.

[fkirc]

Alright, let's keep the PR open until there is a pressing use case for it. By the way, I would rather suggest to allow custom NodeJS-scripts as middleware, something like --middleware=some_node_script.js. Then everyone could roll their own middleware without being dependent on me or someone else merging any middleware into the TypeScript-code.

In fact this is already possible today if someone modifies attranslate's compiled JS-source; for example with some overwrite-script that replaces node_modules/attranslate/dist/core/invoke-translation-service.js with a patched version of invoke-translation-service.js.
It is part of the philosophy of attranslate to make such modifications easily possible, by having well-readable code and not using any obfuscation during TypeScript-compilation.

But like I said, I would be open to merge a middle-ware feature if there is a specific use case for it.