feat: add proxy support

[shazron]

Fixes #13
The module export has changed, thus this is a breaking change and will be a major version bump.

Dependents:

• (use in a Swagger client) feat: add proxy support aio-lib-campaign-standard#89
• (use in openwhisk.js) feat: add proxy support aio-lib-runtime#69
• (pending) and other libs

How Has This Been Tested?

1. unit tests
2. server test harness in unit tests (for testing proxy)
3. manual testing via Dependents PRs above

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[codecov]

Codecov Report

Merging #14 (ba92efa) into master (ce565ee) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master       #14   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            1         5    +4     
  Lines           35       112   +77     
  Branches         7        20   +13     
=========================================
+ Hits            35       112   +77     

Impacted Files	Coverage Δ
src/HttpExponentialBackoff.js	100.00% <100.00%> (ø)
src/ProxyFetch.js	100.00% <100.00%> (ø)
src/SDKErrors.js	100.00% <100.00%> (ø)
src/index.js	100.00% <100.00%> (ø)
src/utils.js	100.00% <100.00%> (ø)

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[moritzraho]

lgtm! nice work 🙂

[shazron]

To facilitate e2e tests in our libraries, we need to extract the test servers so they can be re-used.

Two more things need to be done:

1. Extract the test servers and their tests into their own module
2. We need to create a https-proxy server component to test SSL connections. Currently this is done manually using https://mitmproxy.org/ but we can't automate this, thus we need to create our own (preferably using existing npm modules). A candidate is https://www.npmjs.com/package/http-mitm-proxy

[moritzraho]

fix: add proxy support for exponentialBackoff

Latest changes lgtm

[shazron]

To facilitate e2e tests in our libraries, we need to extract the test servers so they can be re-used.

Two more things need to be done:

1. Extract the test servers and their tests into their own module
2. We need to create a https-proxy server component to test SSL connections. Currently this is done manually using https://mitmproxy.org/ but we can't automate this, thus we need to create our own (preferably using existing npm modules). A candidate is https://www.npmjs.com/package/http-mitm-proxy

Both these items are complete. The test servers are internal right now and are in the process of going open source. Once they are open sourced and published, this PR needs to be modified to use it.