Replace context `HashMap` with `Vec` and add benchmark

[codecov[bot]]

Codecov Report

Base: 63.09% // Head: 63.09% // Increases project coverage by +0.00% :tada:

Coverage data is based on head (8ace8c1) compared to base (e402f11). Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #555 +/- ## ======================================= Coverage 63.09% 63.09% ======================================= Files 55 55 Lines 8995 8996 +1 ======================================= + Hits 5675 5676 +1 Misses 3320 3320 ``` | [Impacted Files](https://codecov.io/gh/sycamore-rs/sycamore/pull/555?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sycamore-rs) | Coverage Δ | | |---|---|---| | [packages/sycamore-core/src/event.rs](https://codecov.io/gh/sycamore-rs/sycamore/pull/555?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sycamore-rs#diff-cGFja2FnZXMvc3ljYW1vcmUtY29yZS9zcmMvZXZlbnQucnM=) | `0.00% <ø> (ø)` | | | [packages/sycamore-reactive/src/lib.rs](https://codecov.io/gh/sycamore-rs/sycamore/pull/555?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sycamore-rs#diff-cGFja2FnZXMvc3ljYW1vcmUtcmVhY3RpdmUvc3JjL2xpYi5ycw==) | `93.98% <ø> (ø)` | | | [packages/sycamore-reactive/src/context.rs](https://codecov.io/gh/sycamore-rs/sycamore/pull/555?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sycamore-rs#diff-cGFja2FnZXMvc3ljYW1vcmUtcmVhY3RpdmUvc3JjL2NvbnRleHQucnM=) | `100.00% <100.00%> (ø)` | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sycamore-rs). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sycamore-rs)

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[github-actions[bot]]

Benchmark Report

• wasm-bindgen: the performance goal
• baseline: performance of sycamore-baseline (typically latest master)
• update: performance of sycamore (typically recent changes)
• diff: measures the improvement of update over the baseline

  
  @@                           Performance Diff                           @@

| wasm-bindgen | baseline | update | diff

##########################################################################

• 01_run1k | 160.43 | 187.35 | 175.41 | -6.37%
• 02_replace1k | 167.66 | 208.01 | 215.15 | +3.43%
• 03_update10th1k_x16 | 470.51 | 497.62 | 425.67 | -14.46%
• 04_select1k | 76.06 | 70.00 | 72.51 | +3.59%
• 05_swap1k | 119.13 | 119.75 | 112.27 | -6.25%
• 06_remove-one-1k | 206.49 | 222.82 | 202.97 | -8.91% 07_create10k | 1636.45 | 2105.44 | 2066.25 | -1.86%
• 08_create1k-after1k_x2 | 405.62 | 451.62 | 473.10 | +4.76%
• 09_clear1k_x8 | 112.28 | 156.25 | 138.22 | -11.54% 21_ready-memory | 1.86 | 1.84 | 1.84 | +0.01% 22_run-memory | 2.84 | 5.54 | 5.53 | -0.04% 23_update5-memory | 3.01 | 5.70 | 5.69 | -0.18% 25_run-clear-memory | 1.92 | 4.36 | 4.36 | -0.00% 26_run-10k-memory | 13.34 | 39.73 | 39.73 | -0.01% 31_startup-ci | 1831.24 | 1986.38 | 2038.83 | +2.64% 32_startup-bt | 0.00 | 0.00 | 0.00 | NaN%
• 33_startup-mainthreadcost | 20.58 | 17.79 | 27.72 | +55.78% 34_startup-totalbytes | 189.33 | 304.05 | 303.90 | -0.05%

  
  Workflow: [3849639513](/sycamore-rs/sycamore/actions/runs/3849639513)
  *Adding new commits will generate a new report*