replace fixed size takenbuffer with linked list (#96)

[dqii]

• replace fixed size takenbuffers array with linked list

• switch copynodes logic to use linked list as well (tests pass when the assert(false) in insert is removed)

• clang-format

---

[codecov[bot]]

Codecov Report

Merging #104 (70e2ddd) into main (5c794a4) will decrease coverage by 0.06%. The diff coverage is 57.89%.

:exclamation: Current head 70e2ddd differs from pull request most recent head 74a5397. Consider uploading reports for the commit 74a5397 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #104 +/- ## ========================================== - Coverage 83.87% 83.82% -0.06% ========================================== Files 13 13 Lines 949 946 -3 Branches 185 183 -2 ========================================== - Hits 796 793 -3 Misses 67 67 Partials 86 86 ``` | [Files Changed](https://app.codecov.io/gh/lanterndata/lanterndb/pull/104?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=lanterndata) | Coverage Δ | | |---|---|---| | [src/hnsw/insert.c](https://app.codecov.io/gh/lanterndata/lanterndb/pull/104?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=lanterndata#diff-c3JjL2huc3cvaW5zZXJ0LmM=) | `81.03% <ø> (ø)` | | | [src/hnsw/retriever.c](https://app.codecov.io/gh/lanterndata/lanterndb/pull/104?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=lanterndata#diff-c3JjL2huc3cvcmV0cmlldmVyLmM=) | `73.33% <50.00%> (-16.33%)` | :arrow_down: | | [src/hnsw/external\_index.c](https://app.codecov.io/gh/lanterndata/lanterndb/pull/104?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=lanterndata#diff-c3JjL2huc3cvZXh0ZXJuYWxfaW5kZXguYw==) | `88.23% <100.00%> (+1.54%)` | :arrow_up: |