fixed docker file generation for C/Ccpp target and python target

[housengw]

C/Ccpp target:
fixed both standalone and federated docker file generation.

Python target:
added standalone docker file generation.

Also added an example at example/C/ContainerizedFederatedHelloWorld

[Soroosh129]

Hi Steven
Why did you close this PR?
You can mark it as a draft PR if you think something needs to be added.

[housengw]

oh i was trying to resolve the merge conflict

[housengw]

converting this to draft because I am getting a

lfc: error: Platform mac os x is not supported
 --> (unknown file):null:1 - Platform mac os x is not supported

error after resolving conflicts

[Soroosh129]

converting this to draft because I am getting a

lfc: error: Platform mac os x is not supported
 --> (unknown file):null:1 - Platform mac os x is not supported

error after resolving conflicts

Hmm, the merge created a weird addPlatformFiles. My guess is that it should look like this. Not sure what happened there.

[Soroosh129]

My guess is that the merge conflict happened because of this line in master:

// All platforms use this one.
coreFiles.add("platform/lf_tag_64_32.h");

[lhstrh]

This looks good! I left a minor comment (and I saw there was also an unaddressed comment from @Soroosh129).