lintcmd: don't print \' in -list-checks and -explain

All the single quotes are written as `\'` in the descriptions. I assume
that's for a good reason, but -list-checks would print:

    % staticcheck -list-checks | grep "'"
    S1003 Replace call to \'strings.Index\' with \'strings.Contains\'
    S1004 Replace call to \'bytes.Compare\' with \'bytes.Equal\'
    S1011 Use a single \'append\' to concatenate two slices
    S1012 Replace \'time.Now().Sub(x)\' with \'time.Since(x)\'
    ...

    % staticcheck -explain S1003
    Replace call to \'strings.Index\' with \'strings.Contains\'

So fix that:

    % staticcheck -list-checks | grep "'"
    S1003 Replace call to 'strings.Index' with 'strings.Contains'
    S1004 Replace call to 'bytes.Compare' with 'bytes.Equal'
    S1011 Use a single 'append' to concatenate two slices
    S1012 Replace 'time.Now().Sub(x)' with 'time.Since(x)'
    ...

    % staticcheck -explain S1003
    Replace call to 'strings.Index' with 'strings.Contains'

As an added bonus, make `-explain s1003` (lower case) work. Seemed too
small of a change to make a new PR for.

lintcmd/cmd.go

@@ -354,7 +354,7 @@ func (cmd *Command) listChecks() int {
 		if c.Doc != nil {
 			title = c.Doc.Title
 		}
-		fmt.Printf("%s %s\n", c.Analyzer.Name, title)
+		fmt.Printf("%s %s\n", c.Analyzer.Name, strings.ReplaceAll(title, `\'`, "'"))
 	}
 	return 0
 }
@@ -366,7 +366,7 @@ func (cmd *Command) printVersion() int {
 
 func (cmd *Command) explain() int {
 	explain := cmd.flags.explain
-	check, ok := cmd.analyzers[explain]
+	check, ok := cmd.analyzers[strings.ToUpper(explain)]
 	if !ok {
 		fmt.Fprintln(os.Stderr, "Couldn't find check", explain)
 		return 1
@@ -375,7 +375,7 @@ func (cmd *Command) explain() int {
 		fmt.Fprintln(os.Stderr, explain, "has no documentation")
 		return 1
 	}
-	fmt.Println(check.Doc)
+	fmt.Println(strings.ReplaceAll(check.Doc.String(), `\'`, "'"))
 	fmt.Println("Online documentation\n    https://staticcheck.dev/docs/checks#" + check.Analyzer.Name)
 	return 0
 }