[tool] Coverage crash fix

[vineethk]

Description

Fixes #15117, #15698, #15032.

Starting point for this PR was #15250, but there are several modifications.

How Has This Been Tested?

• Manually tested each of the scenarios in [Bug][compiler-v2] Coverage testing DevEx issues #15117, [Bug] move coverage tool panics #15698, [Bug] crash in the aptos move coverage tool #15032, and verified that we do not crash.
• Manually tested some handcrafted Move projects for sanity checks.
• Existing tests.

Key Areas to Review

Type of Change

• Bug fix

Which Components or Systems Does This Change Impact?

• Other: Move Coverage Tool

[trunk-io]

⏱️ 9s total CI duration on this PR

Job	Cumulative Duration	Recent Runs
permission-check	5s	🟩
permission-check	4s	🟩
check-branch-prefix	1s	🟩

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[vineethk]

• [tool] Coverage crash fix #15857 👈 (View in Graphite)
• main

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