Add bash completion for spring command

* Added src/main/content/bash_completion.d/spring
* Also made all commands alias to "--<self>" so
"--help" is a synonym for "help" (for instance). This
helps with the completion generation.

[Fixes #54827292]

spring-boot-cli/src/main/content/bash_completion.d/spring

@@ -0,0 +1,36 @@
+# bash completion for spring
+# Installation: source this file locally in a terminal or from 
+# ~/.bashrc or put it in /etc/bash_completions.d (debian)
+
+_spring()
+{
+    local cur prev help helps words cword command commands i
+
+    COMPREPLY=()
+    _get_comp_words_by_ref cur prev words cword
+
+    commands=( `_parse_help spring | sed -e 's/--//'` )
+    if [[ "$prev" == spring ]]; then
+        for command in "${commands[@]}"; do
+            if [[ "${cur}${command#$cur*}" == "$command" ]]; then
+                COMPREPLY+=("$command")
+            fi
+        done
+        return 0
+    else
+        for command in "${commands[@]}"; do
+            if [[ "$prev" == "$command" && "$cur" == -* ]]; then
+                helps=( `_parse_help 'spring help' $prev` )
+                for help in "${helps[@]:2}"; do
+                    if [[ "${cur}${help#$cur*}" == "$help" ]]; then
+                        COMPREPLY+=("$help")
+                    fi
+                done
+                return 0
+            fi
+        done        
+    fi
+
+    _filedir
+
+} && complete -F _spring spring

spring-boot-cli/src/main/java/org/springframework/boot/cli/SpringCli.java

@@ -126,6 +126,9 @@ public class SpringCli {
 	}
 
 	private Command find(String name) {
+		if (name.startsWith("--")) {
+			name = name.substring("--".length());
+		}
 		for (Command candidate : this.commands) {
 			if (candidate.getName().equals(name)) {
 				return candidate;
@@ -143,10 +146,17 @@ public class SpringCli {
 		for (Command command : this.commands) {
 			String usageHelp = command.getUsageHelp();
 			String description = command.getDescription();
-			Log.info(String.format("\n  %1$s %2$-15s\n    %3$s", command.getName(),
+			String name = command.getName();
+			if (!name.startsWith("--")) {
+				name = "--" + name + ", " + name;
+			}
+			Log.info(String.format("\n  %1$s %2$-15s\n    %3$s", name,
 					(usageHelp == null ? "" : usageHelp), (description == null ? ""
 							: description)));
 		}
+		Log.info(String.format("\n  %1$s %2$-15s\n    %3$s", "-d, --debug",
+				"Verbose mode",
+				"Print additional status information for the command you are running"));
 		Log.info("");
 		Log.info("See '" + CLI_APP
 				+ " help <command>' for more information on a specific command.");

spring-boot-cli/src/main/java/org/springframework/boot/cli/command/VersionCommand.java

@@ -27,7 +27,7 @@ import org.springframework.boot.cli.Log;
 public class VersionCommand extends AbstractCommand {
 
 	public VersionCommand() {
-		super("--version", "Show the version");
+		super("version", "Show the version");
 	}
 
 	@Override