[Bug]: bazel_sandbox_plugin is very slow

### What happened?

https://github.com/aspect-build/rules_esbuild/pull/160 added a JavaScript plugin.
Users report on Slack that this new feature in 0.18.0 increases bundling times by an unacceptable amount.

Maybe it can simply be optimized.
Or it could use the esbuild Go API instead if someone has the time to evaluate that and re-write it.

Setting https://github.com/aspect-build/rules_esbuild/blob/main/docs/esbuild.md#esbuild_bundle-bazel_sandbox_plugin to `False` is the workaround, though it reverts to earlier behavior of non-hermetic esbuild sometimes not picking up changes.

### Version

0.18.0

### How to reproduce

_No response_

### Any other information?

_No response_

Review PR 160 and the esbuild_bundle.bazel_sandbox_plugin documentation entry first. Establish a reproducible bundling-time comparison, then evaluate optimizing the JavaScript plugin versus using the esbuild Go API; done means performance improves without losing the hermetic behavior described by the False workaround.

Written by the indexing model from the issue text.