Test command names and search terms for redundancy (#6380)

* Test commands for proper names and search terms

Assert that the `Command.name()` is equal to `Signature.name`

Check that search terms are not just substrings of the command name as
they would not help finding the command.

* Clean up search terms

Remove redundant terms that just replicate the command name.
Try to eliminate substring between search terms, clean up where
necessary.

crates/nu-command/src/conversions/into/binary.rs

@@ -29,7 +29,7 @@ impl Command for SubCommand {
     }
 
     fn search_terms(&self) -> Vec<&str> {
-        vec!["convert", "binary", "bytes", "bin"]
+        vec!["convert", "bytes"]
     }
 
     fn run(

crates/nu-command/src/conversions/into/datetime.rs

@@ -103,7 +103,7 @@ impl Command for SubCommand {
     }
 
     fn search_terms(&self) -> Vec<&str> {
-        vec!["convert", "date", "time", "timezone", "UTC"]
+        vec!["convert", "timezone", "UTC"]
     }
 
     fn examples(&self) -> Vec<Example> {

crates/nu-command/src/conversions/into/filesize.rs

@@ -28,7 +28,7 @@ impl Command for SubCommand {
     }
 
     fn search_terms(&self) -> Vec<&str> {
-        vec!["convert", "number", "size", "bytes"]
+        vec!["convert", "number", "bytes"]
     }
 
     fn run(

crates/nu-command/src/conversions/into/string.rs

@@ -38,7 +38,7 @@ impl Command for SubCommand {
     }
 
     fn search_terms(&self) -> Vec<&str> {
-        vec!["convert", "str", "text"]
+        vec!["convert", "text"]
     }
 
     fn run(