Accept tsconfig alias to tsConfig

[jednano]

🚀 Feature Proposal

Accept tsconfig (all lowercase) as an alias to tsConfig option.

Motivation

tsconfig.json is almost always referred to in the lowercase version, which makes it super simple to overlook that this package requires an uppercase C as tsConfig (a mistake that cost me some unnecessary time today).

Example

Here is the current implementation:

const { tsConfig: tsConfigOpt } = options

I suggest we simply change this to:

const tsConfigOpt = options.tsConfig ?? options.tsconfig ?? true;

This way, you can also remove tsConfigOpt == null from the following "if" statement.

[ahnpnl]

PR is welcome 😀

[jednano]

@ahnpnl done, please see #1565