refactor: make run options have shorthand vars

Simple nitpick refactor to have all run option flags (except hashes
since there isn't really a good shorthand right now, given h is used for
help, and it would be a good idea to be explicit for≠ hashes) have
shorthand vars.

docs/commands.md

@@ -79,8 +79,8 @@ witness run [cmd] [flags]
       --signer-vault-ttl duration                     Time to live for the generated certificate. Defaults to the vault role policy's configured TTL if not provided
       --signer-vault-url string                       Base url of the Vault instance to connect to
   -s, --step string                                   Name of the step being run
-      --timestamp-servers strings                     Timestamp Authority Servers to use when signing envelope
-      --trace                                         Enable tracing for the command
+  -t, --timestamp-servers strings                     Timestamp Authority Servers to use when signing envelope
+  -r, --trace                                         Enable tracing for the command
   -d, --workingdir string                             Directory from which commands will run
 ```
 

options/run.go

@@ -54,8 +54,8 @@ func (ro *RunOptions) AddFlags(cmd *cobra.Command) {
 	cmd.Flags().StringSliceVar(&ro.Hashes, "hashes", []string{"sha256"}, "Hashes selected for digest calculation. Defaults to SHA256")
 	cmd.Flags().StringVarP(&ro.OutFilePath, "outfile", "o", "", "File to write signed data to")
 	cmd.Flags().StringVarP(&ro.StepName, "step", "s", "", "Name of the step being run")
-	cmd.Flags().BoolVar(&ro.Tracing, "trace", false, "Enable tracing for the command")
-	cmd.Flags().StringSliceVar(&ro.TimestampServers, "timestamp-servers", []string{}, "Timestamp Authority Servers to use when signing envelope")
+	cmd.Flags().BoolVarP(&ro.Tracing, "trace", "r", false, "Enable tracing for the command")
+	cmd.Flags().StringSliceVarP(&ro.TimestampServers, "timestamp-servers", "t", []string{}, "Timestamp Authority Servers to use when signing envelope")
 
 	cmd.MarkFlagsRequiredTogether(RequiredRunFlags...)