Handle scalar float input in pybindings

[GregoryComer]

Summary: Add scalar float handling in pybinding code, simliar to existing logic for scalar ints. This lets models take scalar floats as inputs.

Differential Revision: D104910685

[pytorch-bot]

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❌ 3 New Failures, 4 Unrelated Failures

As of commit a773eff with merge base fe98297 ():

NEW FAILURES - The following jobs have failed:

• pull / unittest / linux / linux-job (gh)
  exir/tests/test_joint_graph.py::TestJointGraph::test_joint_graph
• pull / unittest-editable / linux / linux-job (gh)
  exir/tests/test_memory_planning.py::TestMisc::test_multiple_pools_1
• pull / unittest-editable / macos / macos-job (gh)
  exir/emit/test/test_emit.py::TestEmit::test_delegate_deduplicate

FLAKY - The following jobs failed but were likely due to flakiness present on trunk:

• pull / test-qnn-testsuite-linux / test-backend-linux (qnn, models) / linux-job (gh) (detected as infra flaky with no log or failing log classifier)
• pull / unittest / windows / windows-job (gh) (detected as infra flaky with no log or failing log classifier)

BROKEN TRUNK - The following jobs failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• pull / unittest / macos / macos-job (gh) (trunk failure)
  exir/tests/test_joint_graph.py::TestJointGraph::test_joint_graph
• pull / unittest-editable / windows / windows-job (gh) (trunk failure)
  backends/xnnpack/test/recipes/test_xnnpack_recipes.py::TestXnnpackRecipes::test_8a4w_recipe

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[meta-codesync]

@GregoryComer has exported this pull request. If you are a Meta employee, you can view the originating Diff in D104910685.

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