[No Ticket] `--detect-dynamic` less error prone

[meghfossa]

Overview

This PR, makes ldd parsing less error prone, by safely excluding not found cases

Acceptance criteria

For cases such as following, --detect-dynamic analysis should not fatally fail.

    libprotobuf.so.22 => not found
    libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007ffffff4c000)

Testing plan

I relied on automated testings

Risks

N/A

Metrics

N/A

References

N/A

Checklist

• [x] I added tests for this PR's change (or explained in the PR description why tests don't make sense).
• [x] If this PR introduced a user-visible change, I added documentation into docs/.
• [x] If this PR added docs, I added links as appropriate to the user manual's ToC in docs/README.ms and gave consideration to how discoverable or not my documentation is.
• [x] If this change is externally visible, I updated Changelog.md. If this PR did not mark a release, I added my changes into an # Unreleased section at the top.
• [x] If I made changes to .fossa.yml or fossa-deps.{json.yml}, I updated docs/references/files/*.schema.json AND I have updated example files used by fossa init command. You may also need to update these if you have added/removed new dependency type (e.g. pip) or analysis target type (e.g. poetry).
• [x] If I made changes to a subcommand's options, I updated docs/references/subcommands/<subcommand>.md.