Update Python client to support batch insert and search

[peopleig]

batch_insert() takes a list of (DenseVector, Payload) tuples

batch_search() supports multiple formats of input

• List of SearchQuery objects
• List of (DenseVector, Similarity, Limit) tuples
• List of (DenseVector, Similarity) tuples with a global Limit
• List of (DenseVector, Limit) tuples with a global Similarity
• List of DenseVector with global Similarity and Limit

SearchQuery model introduced because using tuples will get cumbersome if the number of fields in a query were to increase