[Tables] Add missing browser mappings

[joheredi]

Fixes #15921

There were 2 issues related to browsers:

1. In one of the util files we are importing "url" instead of the util "./url" which causes URL not to be present in browsers.
2. Missing browser mapping for computeHMACSHA256. Tables don't support NamedKey authentication on browsers for security reasons (risky to have the keys in the browser).
   • Added a shim function that throws if it is attempted to be used in browser. All entry points to this function are already throwing
   • Note: I looked into using @azure/core-crypto however I wasn't able to use it because it exposes an async function and the public API that consumes this is synchronous 😢

[ellismg]

LGTM

[ramya-rao-a]

@chradek Can we log an issue to track the concern that Jose mentioned above around core-crypto?

[chradek]

What is the API in question that is sync and uses crypto?

There is no sync version of SHA256 HMAC crypto support in browsers, so core-crypto can't be changed to use a sync version.

[ellismg]

What is the API in question that is sync and uses crypto?

From a brief look at the code, it's all around generating SAS tokens:

generateAccountSas is one such example, it's a prompt function but uses SHA256 HMAC to sign the SAS signature it generates.