refactor: use import type

Now that we don't depend on `@vue/compiler-sfc` directly, we should only
import types from the package, in case of accidentally depending on the
unlisted dependency.

Author: haoqunjiang

src/descriptorCache.ts

@@ -1,5 +1,5 @@
 import * as fs from 'fs'
-import { SFCDescriptor } from '@vue/compiler-sfc'
+import type { SFCDescriptor } from '@vue/compiler-sfc'
 import { compiler } from './compiler'
 
 const cache = new Map<string, SFCDescriptor>()

src/formatError.ts

@@ -1,4 +1,4 @@
-import { CompilerError } from '@vue/compiler-sfc'
+import type { CompilerError } from '@vue/compiler-sfc'
 import { compiler } from './compiler'
 import chalk = require('chalk')
 

src/index.ts

@@ -6,7 +6,7 @@ import * as loaderUtils from 'loader-utils'
 import hash = require('hash-sum')
 
 import { compiler } from './compiler'
-import {
+import type {
   TemplateCompiler,
   CompilerOptions,
   SFCBlock,

src/pluginWebpack4.ts

@@ -1,6 +1,6 @@
 import * as qs from 'querystring'
 import webpack = require('webpack')
-import { VueLoaderOptions } from './'
+import type { VueLoaderOptions } from './'
 
 const RuleSet = require('webpack/lib/RuleSet')
 

src/pluginWebpack5.ts

@@ -1,6 +1,6 @@
 import * as qs from 'querystring'
-import { VueLoaderOptions } from './'
-import { RuleSetRule, Compiler, Plugin } from 'webpack'
+import type { VueLoaderOptions } from './'
+import type { RuleSetRule, Compiler, Plugin } from 'webpack'
 
 const id = 'vue-loader-plugin'
 const NS = 'vue-loader'

src/resolveScript.ts

@@ -1,10 +1,10 @@
 import webpack = require('webpack')
-import {
+import type {
   SFCDescriptor,
   SFCScriptBlock,
   TemplateCompiler,
 } from '@vue/compiler-sfc'
-import { VueLoaderOptions } from 'src'
+import type { VueLoaderOptions } from 'src'
 import { resolveTemplateTSOptions } from './util'
 import { compiler } from './compiler'
 

src/select.ts

@@ -1,8 +1,8 @@
 import webpack = require('webpack')
-import { SFCDescriptor } from '@vue/compiler-sfc'
-import { ParsedUrlQuery } from 'querystring'
+import type { SFCDescriptor } from '@vue/compiler-sfc'
+import type { ParsedUrlQuery } from 'querystring'
 import { resolveScript } from './resolveScript'
-import { VueLoaderOptions } from 'src'
+import type { VueLoaderOptions } from 'src'
 
 export function selectBlock(
   descriptor: SFCDescriptor,

src/templateLoader.ts

@@ -3,7 +3,7 @@ import * as qs from 'querystring'
 import * as loaderUtils from 'loader-utils'
 import { VueLoaderOptions } from './'
 import { formatError } from './formatError'
-import { TemplateCompiler } from '@vue/compiler-sfc'
+import type { TemplateCompiler } from '@vue/compiler-sfc'
 import { getDescriptor } from './descriptorCache'
 import { resolveScript } from './resolveScript'
 import { resolveTemplateTSOptions } from './util'

src/util.ts

@@ -1,5 +1,5 @@
-import { SFCDescriptor, CompilerOptions } from '@vue/compiler-sfc'
-import { VueLoaderOptions } from '.'
+import type { SFCDescriptor, CompilerOptions } from '@vue/compiler-sfc'
+import type { VueLoaderOptions } from '.'
 
 export function resolveTemplateTSOptions(
   descriptor: SFCDescriptor,