Use camelCase instead of kebab-case for params (breaking change!)

[gregjopa]

This PR makes a breaking interface change for the types for the loadScript(PayPalScriptOptions) loader function. It changes the PayPalScriptOptions interface to use camelCase instead of kebab-case.

I think this would improve the developer experience since JS devs are familiar to camelCase for all the things. Note that we would still pass query params and data attributes as kebab-case under the hood but would hide this from the public interface.

The TypeScript types have been updated to use camelCase format for PayPalScriptOptions and follow this Google JS Style Guide for naming conventions for acronyms.
https://google.github.io/styleguide/jsguide.html#naming-camel-case-defined

Before

loadScript({ 
  "client-id": "test", 
  "merchant-id": ["123", "456", "789"] 
});

After

loadScript({ 
  clientId: "test", 
  merchantId: ["123", "456", "789"] 
});

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (ec977f1) 100.00% compared to head (77b4e4c) 100.00%.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #375   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            2         2           
  Lines          138       128   -10     
  Branches        39        36    -3     
=========================================
- Hits           138       128   -10     

Impacted Files	Coverage Δ
src/utils.ts	100.00% <100.00%> (ø)

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[ravishekhar]

lgtm 👍

[ravishekhar]

Nit: Though I feel its a micro optimization; should we use startsWith() instead of substring()

Perf

[gregjopa]

It's a good call out. Normally I would prefer startsWith() but I think that feature was added to JS in ES6. Right now, paypal-js transpiles to ES5 and has bundle-size checks to keep the library as small as possible.