sc-cli: Fix bugs after switching to clap3 (#10920)

* sc-cli: Fix bugs after switching to clap3

Before switching to clap3 we support cli options like `--reserved-nodes A B` and after you needed to
pass `--reserved-nodes` cli option multiple times `--reserved-nodes A --reserved-nodes B`. This is
fixed by setting `multiple_occurrences(true)` option. This also done for all the other `Vec` cli
options in `sc-cli`. Besides that `--sync` wasn't supporting case insensitive parsing of the value.
This is now also supported. For both regressions a test is added. Besides that the pr removes all
the `rename_all = PascalCase` attributes, because they are not needed. All other `ArgEnum`s were
checked and all are already using `ignore_case(true)`.

* Bring back `PascalCase`, because otherwise it falls back to `kebab-case`...