Add HTTPStatusIntToEnum to VaRestLibrary

[trdwll]

[ufna]

Just a few comments:

1. Let's remove pragma region
2. Check clang-format (it's not formatted for now, see https://teamcity.ufna.dev/buildConfiguration/UfnaDev_VaRest_ClangFormatCheck/507?buildTab=log&focusLine=3&linesState=70)
3. namespace/type enums are deprecated. Even if we took it from epics code, let's change it to the enum class.
4. I think its better to store the Enum in VaRestTypes.h , not the library itself.

[ufna]

Thanks, @trdwll !