Fix method meta error in wasm build

[Conarnar]

Summary

An error would occur when trying to get the metadata for a method containing an input or output that isn't a tensor. This occurs because there wasn't a check for the input/output tag when generating the list of tensor metadata.

Now the list of tensor metadata will have undefined if the input/output in that index is not a tensor.

Test plan

Added unit tests to test the method metadata for a method that has ints in its input and outputs.
Added unit test to check if getMethod works if the module has multiple methods.

Unit tests are in the CI but can be ran with

bash scripts/build_wasm_tests.sh
cd cmake-out-wasm/extension/wasm/test/
npm test # after installing Jest

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/13496

• 📄 Preview Python docs built from this PR

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❌ 2 New Failures

As of commit 71e681d with merge base d6b462d ():

NEW FAILURES - The following jobs have failed:

• pull / android / run-emulator (gh)
  The process '/usr/bin/sh' failed with exit code 255
• pull / unittest / macos / macos-job (gh)
  backends/xnnpack/test/ops/test_conv1d.py::TestConv1d::test_qs8_conv1d_batchnorm_seq

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