Make -I take in a ;-delimited list (#8864)

# Description
Changes `-I` to take in a semicolon-delimited list of paths. Eg) `-I
"/a/b;/foo/bar"`

# User-Facing Changes
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src/command.rs

@@ -258,7 +258,7 @@ impl Command for Nu {
             .named(
                 "include-path",
                 SyntaxShape::String,
-                "set the NU_LIB_DIRS for the given script",
+                "set the NU_LIB_DIRS for the given script (semicolon-delimited)",
                 Some('I'),
             )
             .switch("interactive", "start as an interactive shell", Some('i'))