Install bash completion

From https://github.com/hashcat/hashcat/blob/v6.2.6/extra/tab_completion/hashcat.sh

prepare() from https://github.com/hashcat/hashcat/blob/v6.2.6/extra/tab_completion/install#L144 (Modification applied to make it work, upstream PR https://github.com/hashcat/hashcat/pull/3966)