Hi TN Electronic: Fix partial TSV matching, chemical formula logic, and relative file paths

[shrpawar-alt]

What does this PR do ?

• Fix partial TSV matching to enforce full-word literal fallback (e.g., "robinson")
• Add chemical_names.tsv and resolve unmatched chemical formula logic
• Support relative Unix file paths without a leading slash (e.g., home/desktop)

Before your PR is "Ready for review"

Pre checks:

• Have you signed your commits? Use git commit -s to sign.
• Do all unittests finish successfully before sending PR?
  1. pytest or (if your machine does not have GPU) pytest --cpu from the root folder (given you marked your test cases accordingly @pytest.mark.run_only_on('CPU')).
  2. Sparrowhawk tests bash tools/text_processing_deployment/export_grammars.sh --MODE=test ...
• If you are adding a new feature: Have you added test cases for both pytest and Sparrowhawk here.
• Have you added __init__.py for every folder and subfolder, including data folder which has .TSV files?
• Have you followed codeQL results and removed unused variables and imports (report is at the bottom of the PR in github review box) ?
• Have you added the correct license header Copyright (c) 2023, NVIDIA CORPORATION & AFFILIATES. All rights reserved. to all newly added Python files?
• If you copied nemo_text_processing/text_normalization/en/graph_utils.py your header's second line should be Copyright 2015 and onwards Google, Inc.. See an example here.
• Remove import guards (try import: ... except: ...) if not already done.
• If you added a new language or a new feature please update the NeMo documentation (lives in different repo).
• Have you added your language support to tools/text_processing_deployment/pynini_export.py.

PR Type:

• New Feature
• Bugfix
• Documentation
• Test

If you haven't finished some of the above items you can still open "Draft" PR.

[mgrafu]

it doesn't make sense to hardcode some chemical compounds and not cover others. if we want coverage for this, it would make more sense to have all individual elements and rules to cover their composition

[mgrafu]

let's add these with a tsv instead of hardcoding