ci_find_tools misses changed tools if tool XML is unchanged

[bernt-matthias]

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ci_find_tools --changed_in_commit_range RANGE seems not find changed tools if the main xml file is not changed (e.g. if only scripts or test-data is changed).

Not sure if this is the desired behavior, but the finding such tools would be needed in the IUC PR workflow in the linting step: https://github.com/galaxyproject/tools-iuc/blob/4daa375d022673d2437d609b1865b78c64b04415/.github/workflows/pr.yaml#L156

I guess for each non-xml file one would need to traverse the tree up to the repo root and take the first tool xml that is found in one of these paths.