180 error in replace missing values when a vector in na strings argument

[Karim-Mane]

Changes in this PR are intended to address isse #176 .

This PR is been opened again to address this issue as it was raised together with those fixed in #180 by @avallecam.

With the current changes, the {snakecase} dependency is replaced by {janitor} to benefit from its functionality of renaming numeric column names.

changes also include making sure that column names specified in keep and rename remain unique and not modified during the process.

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[github-actions[bot]]

This pull request:

• Adds 3 new dependencies (direct and indirect)
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[github-actions[bot]]

This pull request:

• Adds 3 new dependencies (direct and indirect)
• Adds 1 new system dependencies
• Removes 0 existing dependencies (direct and indirect)
• Removes 0 existing system dependencies

(Note that results may be inacurrate if you branched from an outdated version of the target branch.)

[github-actions[bot]]

This pull request:

• Adds 3 new dependencies (direct and indirect)
• Adds 1 new system dependencies
• Removes 0 existing dependencies (direct and indirect)
• Removes 0 existing system dependencies

(Note that results may be inacurrate if you branched from an outdated version of the target branch.)