This change makes a bunch of changes to modernize our JavaScript build

process across our products:

Better handle npm workspaces.
Prior to this change, we had a reviewboard/package.json file which was

the "real" JS package file, and a symlink from the repository root into

that (for the purposes of npm install). This then also specified a

"workspaces" key which had .npm-workspaces/*, in which we'd

automatically create symlinks for djblets and reviewboard. This ended up

kind of double-installing packages, where we'd have both the top-level

reviewboard as well as a reviewboard inside the workspaces.
This change removes the symlink, and creates a new top-level

package.json file which just specifies the workspaces and scripts. All

actual dependencies now live only inside the reviewboard/package.json

file.
This allows creating additional symbolic links in the workspace

directory in order to bring in development copies of spina, ink,

beanbag-eslint-plugin, or whatever other JS dependencies on desires.
Depending on which JS packages one wants to include in their workspace,

this may require having a shared parent directory and a symbolic link

from ../node_modules to ./node_modules, since some things like to

resolve to absolute paths and then crawl up the directory tree (looking

at you, tsc).

Update and consolidate JS dependencies.
Several updates have been made to our JS dependencies:

We now rely on the new @beanbag/js-buildkit metapackage for our

  eslint and typescript dependencies.
babel-polyfill has been replaced with core-js and the

useBuiltIns setting for @babel/preset-env (as per Babel's

  documentation). This ends up transforming the core-js library to only

  include what's needed for the browserslist target.
Most other dependencies have been updated to the latest. CodeMirror

  is updated within its major version, since version 6 is completely

  different.
Update to Storybook 10.
Update to ESLint 9.


Remove npm_dependencies and build-npm-deps.py
It used to be that all our JS dependencies were specified inside

reviewboard/dependencies.py and then we would write out a

package.json file on demand. A while back we inverted that so that

package.json was the authoritative list, and we would auto-generate

python code back into dependencies.py. However, none of that stuff was

actually consumed anywhere.
I've removed the build-npm-deps.py script and the associated block

inside reviewboard/dependencies.py.

Stop vendoring jasmine.
We were both getting jasmine-core through npm as well as vendoring a

copy of jasmine 5.1.0 into our lib/js directory. I've changed it so the

js-test-libs index pulls in the relevant jasmine boot files from the

installed jasmine-core, making it easier and more reliable to upgrade in

the future. We also had vendored in sourcemapped-stacktrace, which

I've changed to also come entirely from npm.
I've also ported our old jasmine-hide-filtered and jasmine-sourcemaps

code to TypeScript.

Simplify browserslist.
Instead of a complicated browserslist config, I've changed it to just

specify baseline widely available. This ends up pulling in a few

more older versions of browsers than our old config did, but it seems

like it's the right choice in the current age.

Fix an issue in the page-banner CSS.
The newer version of LESS correctly identified :not('.ink-c-button')

as an error. I've removed the quotes so that CSS builds properly.

Smoke tested the dev server.
Built static media and verified that everything looked correct,

  especially the core-js polyfills.
Ran python tests.
Ran js-tests.
Ran eslint (eek).
Built the rbintegrations extension to verify that static media

  building still worked for that.
Ran build-storybook
Ran the storybook and flipped through the couple components that are

  there. Verified that things worked as expected.