Add QNN EP option context_node_name_prefix to set EPContext node name prefix

[HectorSVC]

Description

Add QNN EP option context_node_name_prefix to set EPContext node name prefix

Motivation and Context

For the case to workaround QNN context PD memory limit, user need split the model into pieces and generate the QNN context model separately. It could happen that the generated EPContext node in separate graph has same node name. This will cause issue if glue those EPContext nodes together into a single model.
To avoid this user can set this context_node_name_prefix for each split pieces to make the node name unique.

[jywu-msft]

one still has to glue separate context nodes together in one graph/model right?
Would another option be to provide that "glue" tool and have the tool update the node names there to ensure uniqueness?
it seems a bit clunky to do it in QNN EP context model generation.

[HectorSVC]

one still has to glue separate context nodes together in one graph/model right? Would another option be to provide that "glue" tool and have the tool update the node names there to ensure uniqueness? it seems a bit clunky to do it in QNN EP context model generation.

It's hard to have a common script to do the glue work. It's so hard to know what the user want to do. I can imagine there's could be many trick work.

[jywu-msft]

one still has to glue separate context nodes together in one graph/model right? Would another option be to provide that "glue" tool and have the tool update the node names there to ensure uniqueness? it seems a bit clunky to do it in QNN EP context model generation.

It's hard to have a common script to do the glue work. It's so hard to know what the user want to do. I can imagine there's could be many trick work.

sync'd with @HectorSVC offline. we agreed that it's probably better to hold off on this PR until the workflow for splitting/gluing back together the model has been finalized.