Add translation memory for SUMM.AI translations into Easy German

[timobrembeck]

Motivation

The translations into Easy German via the SUMM.AI API consume credits on every call, even if we translate the same sentence twice.

Proposed Solution

Add a local translation memory to keep track of the already translated texts and fetch them from the memory instead of translating them again.

Alternatives

• Just ignore the matter
• Wait for SUMM.AI to implement a translation memory

Additional Context

How exactly we store the information is open for debate. A few ideas:

• In-memory cache (fast, but probably not suitable as we would need to store large amounts of data that is accessed very infrequently)
• File-based cache (discuss file forrmat, e.g. XLIFF or the format MemoQ uses for TMs?)