Improve node and node argument name generation

[wschin]

This PR adds the efforts in #3638 to master branch. This change has two benefits.

• it ensures the uniqueness of names at graph level.
• it avoids the change of names when possible. This is quite annoying if ORT keep renaming variables when, for example, adding a new graph transformer.

Q: Why we don't use a global naming manager?
A:

• If we move the name generator out of graph, there will be two places we check if a name is usable: 1) inside graph's name-generating functions 2) inside name manager's name generator. This is error-prone and largely reduces readability.
• Having a global name manager implies that manager knows all the names. However, the implication is not correct. The global name manager is not aware of pre-stored names such as initializer names in ONNX model.
• The above two points may be resolved with a 10x large change. Basically, every places which uses names need to be replaced with some functions in the global name manager.

[wschin]

If Eigen is put in clip.h, it will be included in CUDA kernel's header and trigger a NVCC bug.

[ke1337]

generated_node_names_ [](start = 34, length = 21)

some models seem to have no node names. Will that still be supported?

[wschin]

If the function is called to generate names form them, yes. For example, it will not generate "" if "" is a node name in the model file.

[ke1337]