Tm/xof compat 1 6 5

[tmontaigu]

Add an enum that allows to represent where the CSPRNG for the
CompressedXofKeySet must start. This is to accommodate for the csprng bug
that was fixed in tfhe-csprng 0.9 to still be able to load 1.5.4 (csprng
0.8.1) data correctly

Defaults to first byte, backward_compatibility handles old data that was
versioned with it.

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This change is 

[nsarlin-zama]

Looks nicely handled! Just a small typo

@nsarlin-zama reviewed 4 files and all commit messages, and made 2 comments.
Reviewable status: 4 of 11 files reviewed, 1 unresolved discussion (waiting on SouchonTheo and tmontaigu).

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tfhe/src/high_level_api/xof_key_set/mod.rs line 61 at r1 (raw file):

// 11) SNS Compression Key

/// Holds an [XofSeed] and the byte at which the random generator should start.

Small typo:

Code snippet:

/// Holds a [XofSeed] and the byte at which the random generator should start.