* feat: UDAF implementation backed by DataFusion.
Directly Transplant DataFusion's UDAF related structs, traits and functions, like `AggregateUDF`, `Accumulator` or `create_udaf` etc.
Implement median UDAF on top of it and used in unit testing.
Refs: #61
* feat: UDAF made generically
Refs: #61
* fix: cargo fmt
* fix: use prelude
* fix: uniform the name
* fix: move maybe commonly used functions together
* fix: make comments more clear
* fix: resolve conversations in CR
* fix: store input types in AccumulatorCreator, and use ScalarVector's iterator
* feat: introducing List value and List datatype
* refactor: use ArcSwap instead of Mutext
* refactor: shorten some namings
* refactor: move median UDAF out of tests
* refactor: rename
* feat: aggregate function registry
* fix: make `Value` satisfy ordering again
* fix: clippy warnings
* doc: add "how to write aggregate function"
* fix: address PR comments
* fix: trying to get rid of unwraps
Co-authored-by: luofucong <luofucong@greptime.com>
* Impl TableEngine, bridge to storage
* Impl sql handler to process insert sql
* fix: minor changes and typo
* test: add datanode test
* test: add table-engine test
* fix: code style
* refactor: split out insert mod from sql and minor changes by CR
* refactor: replace with_context with context
* feat: adds scalars mod and enhance vectors
* temp commit
* fix compile error
* Impl pow function with new udf framework
* Adds common-function crate and impl scalars function
* fix: remove used code
* test: adds test for function crate and refactor vectors
* fix: fmt style
* feat: impl numpy.clip function
* feat: improve clip function returning int64 type when arguments do not have float type
* feat: adds more test for vectors
* feat: adds replicate method test for primitive vector
* fix: by code review
* feat: clip function returns uint64 when all arguments type are unsigned
* refactor: improve vectors#only_null
* fix: clippy warning
* fix: clippy warning
* fix: clip should return float64 when arguments have both signed and unsigned types
