Remove Murmurhash in favor of crypto.subtle.digest or just a Map

[Snapstromegon]

Description

Right now murmurhash is used for grouping items in the batchExecutor by the item's metadata.
This is the only place where this dependency is used and there are other hashing algorithms like sha implemented in all modern browsers using the crypto.subtle API.
Even more so, all browsers have a Map implementation that's better than O(n), some (like Chromium) even use a hashtable themselves. In these cases the faro-web-sdk is hashing a value, so the hash can be hashed.

Proposed solution

Remove the dependency for murmurhash-js and instead either use Map directly or use the crypto.subtle.digest() for hashing instead.

Context

This would reduce the bundle size by ~1.2kb or 2% (5.6% of faro-core) and improve performance.

[Snapstromegon]

As far as I can tell Spidermonkey (the JS engine of Firefox) also handles Map objects as a hashmap internally too: https://searchfox.org/mozilla-central/source/js/src/builtin/MapObject.cpp
I don't know how things are on the JavaScriptCore side (engine of Safari/WebKit).

[eskirk]

@Snapstromegon - thanks for the suggestion. I am doing a bit of research to see if we can fall back to using the builtin Map. I definitely love to remove dependencies when possible so I am hoping you are right. going to discuss with the team and see what our best approach should be.

[eskirk]

after doing a bit of research into WebKit, we have decided to use plain Maps and remove the murmurhash dependency.

here is the PR - thanks for the suggestion 👍🏼