feat(web-api): add request interceptor and HTTP adapter config to WebClient [ISSUE-2073]

[mtjandra]

Summary

Resolves #2073

Features

• ability to configure one axios request interceptor
  • useful for clients who would like to manipulate outgoing requests to conform to their custom proxies
• ability to configure an axios adapter
  • useful for client who would like to used their existing http client
    • ex: client may have a dedicated http client configured to be used with their internal proxy

Contribution Pre-Requisites

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.

[salesforce-cla]

Thanks for the contribution! Before we can merge this, we need @mtjandra to sign the Salesforce Inc. Contributor License Agreement.

[codecov]

Codecov Report

Attention: Patch coverage is 96.23656% with 7 lines in your changes missing coverage. Please review.

Project coverage is 91.83%. Comparing base (2af216c) to head (5dabe0f).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2076      +/-   ##
==========================================
+ Coverage   91.75%   91.83%   +0.07%     
==========================================
  Files          38       38              
  Lines       10093    10264     +171     
  Branches      631      646      +15     
==========================================
+ Hits         9261     9426     +165     
- Misses        820      826       +6     
  Partials       12       12              

Flag	Coverage Δ
cli-hooks	95.23% <ø> (ø)
cli-test	95.69% <ø> (ø)
oauth	77.39% <ø> (ø)
socket-mode	58.22% <ø> (ø)
web-api	96.88% <96.23%> (-0.02%)	⬇️
webhook	96.65% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

[filmaj]

Thanks so much for the PR! I think this is heading in a great direction. I left many questions for my own education and to help inform my future reviews as well.

One higher-level question: what is the intention behind exposing both an adapter option as well as requestInterceptor? How/why would consumers use either/or? Would they use both in any situation? The request interceptor makes sense to expose, but based on the axios docs, it seems adapter is mainly for use for testing (https://axios-http.com/docs/req_config)?

Also, I think we may need to add something to our docs about this new feature. Looking at the right menu bar for the web-api docs here, perhaps a new section on request interceptors / modifiers would be in order? What do you think?

[filmaj]

Awesome work! Left a few minor documentation suggestions; once applied or rejected, I will merge this in.

Thank you so much for your work here and patience with me during review, it is greatly appreciated 🙇

[mtjandra]

Awesome work! Left a few minor documentation suggestions; once applied or rejected, I will merge this in.

Thank you so much for your work here and patience with me during review, it is greatly appreciated 🙇

Thank you for helping me with this and being responsive! I've addressed your comments and have rebased with main