Do not use deprecated /uploads/tx_luxletter for ImageEmbedding

[bzgaLindner]

Since TYPO3 12.4, folder "uploads" is deprecated. In some environments, it is forbidden for applications to to create folders on root level.

Luxletter should use a different configurable folder for generating temporary images for newsletters.

Thanks in advance!

[einpraegsam]

Thx, this can be added to our backlock as feature request @lefloe

[lefloe]

Added it. Thx for the feedback @bzgaLindner !