feat(compositiontest): add composition tests

[haarchri]

Description of your changes

• add composition tests
• remove unused providerconfig
• add default value in xrd
• update example to have an xr instead of an claim

Fixes #

I have:

• Read and followed Upbound's contribution process.
• Run make reviewable to ensure this PR is ready for review.
• Added backport release-x.y labels to auto-backport this PR, as appropriate.

How has this code been tested

up test run tests/*
  ✓   Parsing tests                                                                                                                                  
  ✓   Checking dependencies
  ✓   Generating language schemas
  ✓   Building functions
  ✓   Building configuration package
  ✓   Pushing embedded functions to local daemon                                                                                                     
  ✓   Assert test-xstoragebucket                                                                                                                     
  ✓   Assert test-xstoragebucket-default                                                                                                             
  ✓   Assert test-xstoragebucket                                                                                                                     
 SUCCESS  
 SUCCESS  Tests Summary:
 SUCCESS  ------------------
 SUCCESS  Total Tests Executed: 3
 SUCCESS  Passed tests:         3
 SUCCESS  Failed tests:         0

[adamwg]

lgtm