feat: specify --init filename/path (#2018)

* feat: specify init filename with --taskfile flag

previously, it was not possible to specify which filename to use when initializing a new Taskfile as it was hardcoded as "Taskfile.yml".

now the --taskfile flag specifies where to write the file to, and the first * contained in it will be replaced by "Taskfile", so `task -it *.yaml` will create a `Taskfile.yaml` file.

* docs: update CLI reference

* fix Flags header being inside tip admonition
* change -t flag's default column and add a description
* add Default Filenames section

* docs: revert adding Default Filenames section

I didn't realize it already existed elsewhere.

* refactor: use path instead of filepath on InitTaskFile

as requested to prevent ambiguity with the stdlib package.

* fix TestInit (incorrectly merged)

* docs: remove outdated info on --taskfile flag

* refactor task initialization changes

- remove const DefaultTaskInitFilename from taskfile/taskfile.go
- revert description of Entrypoint flag
- make InitTaskfile accept a path to either a file or a directory, and join the default Taskfile name+ext to it if it is a directory
- take the target file path from the first argument instead of the Entrypoint flag
- detect extension-only filenames (".yaml") instead of replacing "*" with "Taskfile"
- use different format in success log so that it makes sense at different paths than the current dir

* print colon instead of "at"

it's a lot cleaner in most cases.

* rewrite init tests

test both initializing to a directory path and a file path

* return final path from InitTaskfile

...and print it's relative representation

* fix lint error (ineffassign)

* use filepathext.TryAbsToRel() instead

* define and use filepathext.IsExtOnly()

* link to default filenames list in cli ref docs

(specifically in the --taskfile flag description)

cmd/task/task.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"os"
+	fp "path/filepath"
 	"strings"
 
 	"github.com/spf13/pflag"
@@ -13,6 +14,7 @@ import (
 	"github.com/go-task/task/v3/args"
 	"github.com/go-task/task/v3/errors"
 	"github.com/go-task/task/v3/internal/experiments"
+	"github.com/go-task/task/v3/internal/filepathext"
 	"github.com/go-task/task/v3/internal/flags"
 	"github.com/go-task/task/v3/internal/logger"
 	"github.com/go-task/task/v3/internal/sort"
@@ -77,18 +79,28 @@ func run() error {
 		if err != nil {
 			return err
 		}
-
-		if err := task.InitTaskfile(os.Stdout, wd); err != nil {
+		args, _, err := getArgs()
+		if err != nil {
+			return err
+		}
+		path := wd
+		if len(args) > 0 {
+			name := args[0]
+			if filepathext.IsExtOnly(name) {
+				name = filepathext.SmartJoin(fp.Dir(name), "Taskfile"+fp.Ext(name))
+			}
+			path = filepathext.SmartJoin(wd, name)
+		}
+		finalPath, err := task.InitTaskfile(os.Stdout, path)
+		if err != nil {
 			return err
 		}
-
 		if !flags.Silent {
 			if flags.Verbose {
 				log.Outf(logger.Default, "%s\n", task.DefaultTaskfile)
 			}
-			log.Outf(logger.Green, "%s created in the current directory\n", task.DefaultTaskFilename)
+			log.Outf(logger.Green, "Taskfile created: %s\n", filepathext.TryAbsToRel(finalPath))
 		}
-
 		return nil
 	}