Allow to set local variables

[yubiuser]

• What does this PR aim to accomplish?:

In POSIX, local (for variables) is undefined. However, most real-world shells support it.
https://github.com/koalaman/shellcheck/wiki/SC3043#exceptions

For core we decided to use local and suppress the warning. This PR does the same for PADD and sets a few variables to local.

The majority of the shown diffs is only indention change according to our editorconfig.

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