feat: keep internal provider enable

[farnabaz]

• Always keep internal provider available
• Create ipx option inside image module options to control behavior of ipx
• Rename local provider to ipx and warn if users define a provider with name ipx
• Update docs

close #57

[codecov-io]

Codecov Report

Merging #60 into master will decrease coverage by 0.12%.
The diff coverage is 75.00%.

@@            Coverage Diff             @@
##           master      #60      +/-   ##
==========================================
- Coverage   70.69%   70.56%   -0.13%     
==========================================
  Files          21       21              
  Lines         546      547       +1     
  Branches      129      130       +1     
==========================================
  Hits          386      386              
- Misses        158      159       +1     
  Partials        2        2              

Impacted Files	Coverage Δ
src/providers/ipx/index.ts	100.00% <ø> (ø)
src/providers/ipx/runtime.ts	100.00% <ø> (ø)
src/index.ts	83.95% <75.00%> (-1.05%)	⬇️

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