vector search: full support all column types

[sivukhin]

Context

This PR implement full set of operations for 1bit and f64 vector data types. This includes:

• Ability to create ANN index: see vector-f64-index and vector-1bit-index tests
• Set of vector function with basic operation support: vector_extract / vector64 / vector1bit

Also, this PR changes the behaviour of vectorTT functions - before they returned binary blob as is which is weird (for example, vector64(vector32('[1]')) returned binary blob corresponding to vector32. This PR changes this behaviour and implement proper conversion between vector types - so now vectorTT always returns vector of the specified type

Changes

• Introduce FLOAT1BIT / F1BIT_BLOB types for 1bit bit-vectors
• Allow ANN index creation for any valid column type (f32 / f64 / 1bit so far)
• Implement vector1bit conversion function + change the behaviour of all other conversion functions
• Change compress_neighbors setting parameter from 1bit to float1bit to be consistent with type names
  • This is potentially breaking change - but since we introduced support of compress_neighbors only recently and didn't published sqld version with its support - I think we are safe to change this now
• Self-sufficient on-disk format implemented for 1bit vectors. It looks like this:

  
  [data[0] as u8] [data[1] as u8] ... [data[(dims + 7) / 8] as u8] [_ as u8; padding]? [leftover as u8] [3 as u8]

• every data byte (except for the last) represents exactly 8 components of the vector
• last data byte represents [1..8] components of the vector
• optional padding byte ensures that leftover byte will be written at the odd blob position (0-based)
• leftover byte specify amount of trailing bits in the blob without last 'type'-byte which must be omitted (so, vector dimensions are equal to 8 * (blob_size - 1) - leftover)
• last 'type'-byte is mandatory for float1bit vectors