Improve compression of Tile Index

[MichaelKreil]

Currently, the Tile Index is always compressed using the Brotli algorithm to reduce its size. However, Brotli can be quite demanding, particularly on microcontrollers.
Alternatives could include:

• simpler compression, such as gzip, LZW/..., RLE
• varint-based variables, see: use varint (variable-width integers) instead of u64 #9

The good thing is: Since we have a lot of real data (osm.*.versatiles), we can measure the size of the compressed Tile Index for each approach.