…etsentry/sentry-replay#320)

Align the scripts in `package.json` with the scripts we use in the JS SDK repo. Doing this now doesn't hurt us and it's one less thing to worry about when migrating. Admittedly, the `build:*` scripts look a little scary now but this is just because I wanted to preserve the separate build scripts for worker and core. Therefore, we'll end up with a few more scripts than we have in most other SDKs (s.g. [Svelte](https://github.com/getsentry/sentry-javascript/blob/d22380097b70bc503613cebbf2b914175174221c/packages/svelte/package.jsongetsentry/sentry-replay#L34-L42)).

In the monorepo, we don't set env variables for prod vs. dev builds. I still need to think about what we're going to do about them but we can make these changes iteratively. 

Here's a quick overview of the most important changes. All these scripts are used in the monorepo, not just by us but also by CI, so we need to align them:
* `build` now serves as a "default" build command. I renamed what used to be the `build` script to `build:rollup` (which is also consistent with the monorepo). I left `build:prod` from devEx reasons for now but we can remove it after migrating.
* `build:dev` basically remains unchanged as it's already mostly consistent with the monorepo 
* Added `build:watch` and `build:dev:watch` to re-build on file changes. I think previously, the `--watch` param was only applied to `build-core` but I figured we could also watch for worker changes. Which is why I added the `build:all:watch` sub-script to do this. I left the `dev` script for now to not disturb devEx but after migrating we can remove it, as it isn't used in the monorepo at all.
* Added `build:npm` script to pack a tarball when publishing. In the monorepo, we use a script that makes some changes to `package.json` before packing. We'll need to add this here as well but not now, as it requires more changes. Also, I changed the "Build" GH workflow to use this command instead of `npm pack`.
* Added `lint` and `fix` scripts that use eslint and prettier. I left the original commands eslint untouched, just changed the script names around it (and added the prettier stuff)

I added the `npm-run-all` dev dependency for the time being, to get the `run-p/s` commands we use in the monorepo. After migrating, we can remove the dependency again from this package because it's registered as a top-level dependency in the monorepo.