Mis-recognize .ts(MPEG2) as typescript source

[dmc31a42]

Issue Type: Bug

VS code recognize .ts(MPEG2) file as TypeScript source file disregarding 'rootDir' option in 'tsconfig.json'

VS Code version: Code 1.53.2 (622cb03, 2021-02-11T11:48:04.245Z)
OS version: Windows_NT x64 10.0.19042

System Info

Item	Value
CPUs	Intel(R) Core(TM) i5-4690 CPU @ 3.50GHz (4 x 3499)
GPU Status	2d_canvas: enabled gpu_compositing: enabled multiple_raster_threads: enabled_on oop_rasterization: enabled opengl: enabled_on protected_video_decode: unavailable_off rasterization: enabled skia_renderer: enabled_on video_decode: enabled vulkan: disabled_off webgl: enabled webgl2: enabled
Load (avg)	undefined
Memory (System)	15.85GB (3.44GB free)
Process Argv	--crash-reporter-id f4ea839a-7e81-4a89-9e60-31c1c8382134
Screen Reader	no
VM	50%

Extensions (18)

Extension	Author (truncated)	Version
ng-template	Ang	11.2.3
vscode-django	bat	1.3.0
angular-schematics	cyr	4.10.1
jquerysnippets	don	0.0.1
python-extension-pack	don	1.6.0
prettier-vscode	esb	5.9.2
go	gol	0.22.1
papyrus-lang-vscode	joe	2.23.1
Angular2	joh	11.0.0
MagicPython	mag	1.1.0
python	ms-	2021.2.582707922
jupyter	ms-	2021.2.603412351
remote-wsl	ms-	0.53.4
cpptools	ms-	1.2.2
debugger-for-chrome	msj	4.12.12
vsfire	tob	1.4.1
vscodeintellicode	Vis	1.2.11
jinja	who	0.0.8

A/B Experiments

vsliv368:30146709
vsreu685:30147344
python383:30185418
pythonvspyt617cf:30253240
vspor879:30202332
vspor708:30202333
vspor363:30204092
vstry244cf:30256637
pythonvsdeb440:30248342
pythonvsded773:30248341
pythonvspyt875:30259475

[mjbvz]

Duplicate of microsoft/TypeScript#21136