snippet(go): reformat & revise snippets for consistency

This pull request introduces consistent formatting changes to various Go
code snippets in the 'go-mode' directory. The changes include:

- Adding spaces between function parameters and return types.
- Formatting import statements to use parentheses for multiple imports.
- Updating struct snippets to include a name for the struct type.
- Updating the 'switch' snippet to include an expression.
- Adding `type` for creating a new struct or interface.

**Changes Made:**
- In 'go-mode/f' and 'go-mode/func', added spaces between function
  parameters and return types to follow go convention.
- In 'go-mode/method', added spaces between function parameters and
  return types to follow go convention.
- In 'go-mode/imp' and 'go-mode/import', reformatted import
  statements to use parentheses for multiple imports.
- In 'go-mode/struct', added a name for the struct type for clarity.
- Add a new file `go-mode/type` for creating a new struct or interface.
- In 'go-mode/switch', updated the 'switch' snippet to include an
  expression for better usage.

Author: weidaolee

go-mode/f

@@ -1,6 +1,6 @@
 # -*- mode: snippet -*-
 # name: func ...(...) ... { ... }
 # --
-func ${1:name}(${2:args})${3: return type} {
+func ${1:name}(${2:args}) ${3:return type}{
     `%`$0
 }

go-mode/fm

@@ -1,6 +1,6 @@
 # -*- mode: snippet -*-
 # name: func (target) name(args) (results) { ... }
 # --
-func (${1:target}) ${2:name}(${3:args})${4: return type} {
+func (${1:target}) ${2:name}(${3:args}) ${4:return type}{
     $0
 }

go-mode/func

@@ -1,6 +1,6 @@
 # -*- mode: snippet -*-
 # name: func ...(...) ... { ... }
 # --
-func ${1:name}(${2:args})${3: return type} {
+func ${1:name}(${2:args}) ${3:return type}{
     `%`$0
 }

go-mode/imp

@@ -1,4 +1,6 @@
 # -*- mode: snippet -*-
 # name: import
 # --
-import ${1:package}$0
+import (
+    ${1:package}$0
+)

go-mode/import

@@ -1,4 +1,6 @@
 # -*- mode: snippet -*-
 # name: import
 # --
-import ${1:package}$0
+import (
+    ${1:package}$0
+)

go-mode/method

@@ -1,6 +1,6 @@
 # -*- mode: snippet -*-
 # name: func (target) name(args) (results) { ... }
 # --
-func (${1:target}) ${2:name}(${3:args})${4: return type} {
+func (${1:target}) ${2:name}(${3:args}) ${4:return type}{
     $0
 }

go-mode/struct

@@ -1,6 +1,6 @@
 # -*- mode: snippet -*-
 # name: type ... struct { ... }
 # --
-type $1 struct {
+type ${1:name} struct {
     `%`$0
 }

go-mode/switch

@@ -3,7 +3,7 @@
 # key: switch
 # uuid: switch
 # --
-switch {
-    case ${1:cond}:
+switch ${1:express}{
+    case ${2:cond}:
          $0
 }

go-mode/type

@@ -0,0 +1,6 @@
+# -*- mode: snippet -*-
+# name: type ... ... { ... }
+# --
+type ${1:name} ${2:struct | interface} {
+    `%`$0
+}