feat: Rename duck_exec() to db_exec() and duck_*() to read_*_duckdb()

[krlmlr]

Closes #210.

[github-actions]

This is how benchmark results would change (along with a 95% confidence interval in relative change) if 34c8777 is merged into main:

• ✔️001_tpch_01: 23.8ms -> 24ms [-3.3%, +5%]
• ✔️001_tpch_02: 68.7ms -> 68.9ms [-0.67%, +1.17%]
• ❗🐌001_tpch_03: 39.5ms -> 40ms [+0.13%, +2.54%]
• ✔️001_tpch_04: 22.4ms -> 22.4ms [-0.82%, +0.77%]
• ✔️001_tpch_05: 57.9ms -> 58.1ms [-0.63%, +1.43%]
• ✔️001_tpch_06: 14.4ms -> 14.6ms [-1.86%, +3.51%]
• ❗🐌001_tpch_07: 75.4ms -> 76.6ms [+0.32%, +2.94%]
• ✔️001_tpch_08: 99.3ms -> 99.4ms [-0.69%, +0.94%]
• ✔️001_tpch_09: 73.8ms -> 73.8ms [-0.96%, +0.84%]
• ✔️001_tpch_10: 48.9ms -> 48.9ms [-0.48%, +0.81%]
• ✔️001_tpch_11: 32.4ms -> 32.4ms [-0.75%, +0.59%]
• ✔️001_tpch_12: 27.5ms -> 27.7ms [-1.61%, +2.87%]
• ✔️001_tpch_13: 25.7ms -> 25.6ms [-2.52%, +2.25%]
• ✔️001_tpch_14: 20.5ms -> 20.7ms [-1.19%, +2.38%]
• ✔️001_tpch_15: 31.8ms -> 31.7ms [-1.64%, +0.59%]
• ✔️001_tpch_16: 39.9ms -> 40.2ms [0%, +1.65%]
• ✔️001_tpch_17: 26.1ms -> 26.1ms [-0.7%, +0.88%]
• ✔️001_tpch_18: 22.7ms -> 22.4ms [-3.28%, +0.47%]
• ✔️001_tpch_19: 68.1ms -> 68.1ms [-0.78%, +0.77%]
• ✔️001_tpch_20: 50.7ms -> 50.8ms [-0.42%, +0.73%]
• ✔️001_tpch_21: 79.6ms -> 79.8ms [-0.78%, +1.37%]
• ✔️001_tpch_22: 68.4ms -> 68.3ms [-1.14%, +0.78%]
• ✔️010_tpch_01: 81.3ms -> 81.5ms [-4.85%, +5.55%]
• ✔️010_tpch_02: 69.9ms -> 70.6ms [-0.36%, +2.51%]
• ✔️010_tpch_03: 59.2ms -> 60.2ms [-0.55%, +3.67%]
• ✔️010_tpch_04: 42.7ms -> 42.9ms [-1.36%, +2.15%]
• ✔️010_tpch_05: 90.6ms -> 90.9ms [-1.09%, +1.79%]
• ✔️010_tpch_06: 32.9ms -> 31.9ms [-9.59%, +3.14%]
• ✔️010_tpch_07: 107ms -> 108ms [-0.75%, +1.24%]
• ✔️010_tpch_08: 129ms -> 128ms [-1.04%, +0.47%]
• ✔️010_tpch_09: 116ms -> 116ms [-1.16%, +1.62%]
• ✔️010_tpch_10: 74.7ms -> 74.9ms [-1.38%, +1.96%]
• ✔️010_tpch_11: 38.3ms -> 38.9ms [-3.22%, +6.38%]
• ✔️010_tpch_12: 57.7ms -> 59ms [-2.49%, +6.91%]
• ✔️010_tpch_13: 52.7ms -> 52.8ms [-1.19%, +1.55%]
• ✔️010_tpch_14: 38.1ms -> 37.7ms [-3.4%, +1.7%]
• ✔️010_tpch_15: 56.6ms -> 54.1ms [-10.34%, +1.46%]
• ✔️010_tpch_16: 45.1ms -> 44.8ms [-3.93%, +2.61%]
• ✔️010_tpch_17: 54.6ms -> 54.2ms [-3.64%, +2.34%]
• ✔️010_tpch_18: 55.4ms -> 53.5ms [-10.34%, +3.55%]
• ✔️010_tpch_19: 117ms -> 117ms [-1.52%, +1.98%]
• ✔️010_tpch_20: 68.3ms -> 66.4ms [-6.52%, +1.07%]
• ✔️010_tpch_21: 240ms -> 239ms [-3.34%, +2.01%]
• ✔️010_tpch_22: 77.5ms -> 77.1ms [-4.13%, +2.97%]
• ✔️100_tpch_01: 324ms -> 315ms [-21.94%, +16.26%]
• ✔️100_tpch_02: 126ms -> 126ms [-2.32%, +3.25%]
• ✔️100_tpch_03: 179ms -> 184ms [-5.16%, +10.34%]
• ✔️100_tpch_04: 159ms -> 151ms [-14.45%, +3.98%]
• ✔️100_tpch_05: 267ms -> 265ms [-13.67%, +11.96%]
• ✔️100_tpch_06: 103ms -> 101ms [-16.3%, +12.06%]
• ✔️100_tpch_07: 241ms -> 238ms [-4.45%, +1.83%]
• ✔️100_tpch_08: 266ms -> 267ms [-13.33%, +13.83%]
• ✔️100_tpch_09: 329ms -> 342ms [-9.58%, +17.25%]
• ✔️100_tpch_10: 217ms -> 215ms [-5.09%, +3.27%]
• ✔️100_tpch_11: 92.9ms -> 84ms [-39.22%, +20.08%]
• ✔️100_tpch_12: 197ms -> 196ms [-11.24%, +9.58%]
• ✔️100_tpch_13: 326ms -> 322ms [-9.89%, +7.21%]
• ✔️100_tpch_14: 124ms -> 121ms [-18.59%, +14.63%]
• ✔️100_tpch_15: 207ms -> 206ms [-13.37%, +13.09%]
• ✔️100_tpch_16: 127ms -> 133ms [-18.88%, +29.75%]
• ✔️100_tpch_17: 181ms -> 174ms [-15.84%, +7.94%]
• ✔️100_tpch_18: 198ms -> 195ms [-15.3%, +12.86%]
• 🚀100_tpch_19: 319ms -> 282ms [-15.5%, -7.98%]
• ✔️100_tpch_20: 173ms -> 171ms [-10.57%, +7.32%]
• ✔️100_tpch_21: 1.32s -> 1.32s [-4.46%, +4.8%]
• ✔️100_tpch_22: 176ms -> 179ms [-9.06%, +13.18%]

Further explanation regarding interpretation and methodology can be found in the documentation.