TypeScript files are not syntax highlighted, .tsx files work with CodeMirror

Created by: scalabilitysolved

Problem

TypeScript files don't have syntax highlighting in our Sourcegraph repo, such as: https://sourcegraph.com/github.com/sourcegraph/sourcegraph/-/blob/client/web/src/components/externalServices/backend.ts

Files with .tsx extension however do have syntax highlighting from the same repo: https://sourcegraph.com/github.com/sourcegraph/sourcegraph/-/blob/client/web/src/components/externalServices/ExternalServicesPage.tsx