Gather a list of new features for 0.4.0 release

[prrao87]

We will soon be releasing Kùzu 0.4.0 with a host of updates including a new storage format. Let's use this space to track and update the new features that we will cover in our group meeting. I'll start off by listing a few of them based on issues/PRs that I've been following, but any of the maintainers are welcome to add to this.

Domain	Issue/PR
Storage	#2912: Unify many-to-one and many-to-many storage
I/O	#2853, #2964, #3171: Support import/export database from/to different versions of Kùzu
I/O	#2979, #2994, #2999: Improve string copying performance through ColumnChunks and string dictionary caching
I/O	#2999: Chunk-at-a-time inserts
I/O	#3105: Improved performance in copy-to-parquet
Types	#3150, #3170, #3057: Rework fixed-list layout & rename FIXED_LIST to ARRAY and VAR_LIST to LIST
PyArrow backend	#3058, #3152: Support PyArrow backend for pandas
PyArrow backend	#3158: Support PyArrow map scanning
Extensions	#3052, #3139, #3071: DuckDB and Postgres scanners
Usability	#3126: Support read after update in a single query transaction
Usability	#3140: Prepare statement improvements

[prrao87]

Closing this. Continued in #3280.