Modify MySqlSequentialGuidValueGenerator to specify more accurate version introduced in newer RFC 9562

[lauxjpn]

Our current implementation of MySqlSequentialGuidValueGenerator references the now obsolete RFC 4122, which has been superseded by RFC 9562.

RFC 9562 introduces additional standard versions, of which 6 and 7 are database optimized UUID variants and 8 is a custom UUID variant.

We currently use version 4 (random) for all cases and should consider modifying our implementation to indicate the appropriate newer version instead (which might be 8 in the case of MySqlGuidFormat.LittleEndianBinary16, see RFC 9562: 6 - UUID Best Practices: 6.11 - Sorting).

This came up in #1996.