[WIP] Initial support of table function

[wangfenjin]

This is based on @Mause 's https://github.com/Mause/duckdb-extension-framework

It works (refer test_table_function), but I'm thinking about design a more safe and high level API, similiar to rusqlite vtab, So need more time to merge the MR

If anyone interested to work on this base on this version can let me know

related to #102 #79

[wangfenjin]

CI failed because of documentation

Some notes about next steps:

1. value and related API are don't directly related to table function, but will be used if user want to implement a table function, because user need these API to generate the result set. So we need to make these class of API easy to use
2. table-functions and related API are used for register the table function, we should design the API simliar to Module and VTab, to make it easy for user to define the table function as normal rust code, with less unsafe code.
3. We can implement an arrow_scan() table function as an show case and also to verify our API design is good enough

[changhiskhan]

@wangfenjin we're working on a rust implementation of lance data format and would be interested in seeing if your PR here can provide an easy way for us to write a Lance Scanner (comes out as Arrow) + replacement scan function (so basically item 3 in your next steps). Are you planning to substantially change the API here?

[codecov]

Codecov Report

Merging #112 (8fddbf7) into main (d4f5c26) will decrease coverage by 1.12%.
The diff coverage is 50.00%.

❗ Current head 8fddbf7 differs from pull request most recent head 16035a8. Consider uploading reports for the commit 16035a8 to get more accurate results

@@            Coverage Diff             @@
##             main     #112      +/-   ##
==========================================
- Coverage   59.47%   58.36%   -1.12%     
==========================================
  Files          26       28       +2     
  Lines        1483     1638     +155     
==========================================
+ Hits          882      956      +74     
- Misses        601      682      +81     

Impacted Files	Coverage Δ
src/table_function/function.rs	40.50% <40.50%> (ø)
src/table_function/mod.rs	57.14% <57.14%> (ø)
src/lib.rs	75.78% <66.66%> (-3.56%)	⬇️
src/inner_connection.rs	85.93% <100.00%> (+0.69%)	⬆️
src/row.rs	58.79% <100.00%> (ø)

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[wangfenjin]

in favor of #138