chore(typescript): Remove baseUrl in anticipation for deprecation. (#90413)

[We recently tried to build the Sentry
codebase](microsoft/typescript-go#807) with
[the native port of the TypeScript
compiler](https://github.com/microsoft/typescript-go). Unfortunately,
the compiler issued a flood of errors because the Sentry project relies
on `baseUrl` which we are leaning towards removing.

Path mapping will still be supported - but `baseUrl` has not been
required for path mapping since TypeScript 4.1, and has been discouraged
from use. `baseUrl` occasionally permits paths that may not be intended
to be valid (e.g. importing from `static/app/foo/Bar` instead of
`sentry/foo/Bar`). It may also be the case that `baseUrl` can result in
extra lookups, but don't quote me on that.

Instead, each path can be given an explicit relative prefix (or
optionally use `${configDir}`, though that is likely not ideal much of
the time). This PR does exactly that and future-proofs the Sentry
codebase.

### Legal Boilerplate

Look, I get it. The entity doing business as "Sentry" was incorporated
in the State of Delaware in 2015 as Functional Software, Inc. and is
gonna need some rights from me in order to utilize my contributions in
this here PR. So here's the deal: I retain all rights, title and
interest in and to my contributions, and by keeping this boilerplate
intact I confirm that Sentry can use, modify, copy, and redistribute my
contributions, under Sentry's choice of terms.

Author: DanielRosenwasser

config/tsconfig.base.json

@@ -95,19 +95,18 @@
     "experimentalDecorators": true,
     "resolveJsonModule": true,
 
-    "baseUrl": "../",
     "paths": {
-      "sentry/*": ["static/app/*"],
-      "sentry-fixture/*": ["tests/js/fixtures/*"],
-      "sentry-test/*": ["tests/js/sentry-test/*"],
-      "getsentry-test/*": ["tests/js/getsentry-test/*"],
-      "sentry-images/*": ["static/images/*"],
-      "sentry-locale/*": ["src/sentry/locale/*"],
-      "sentry-logos/*": ["src/sentry/static/sentry/images/logos/*"],
-      "sentry-fonts/*": ["static/fonts/*"],
-      "getsentry/*": ["static/gsApp/*"],
-      "getsentry-images/*": ["static/images/*"],
-      "admin/*": ["static/gsAdmin/*"]
+      "sentry/*": ["../static/app/*"],
+      "sentry-fixture/*": ["../tests/js/fixtures/*"],
+      "sentry-test/*": ["../tests/js/sentry-test/*"],
+      "getsentry-test/*": ["../tests/js/getsentry-test/*"],
+      "sentry-images/*": ["../static/images/*"],
+      "sentry-locale/*": ["../src/sentry/locale/*"],
+      "sentry-logos/*": ["../src/sentry/static/sentry/images/logos/*"],
+      "sentry-fonts/*": ["../static/fonts/*"],
+      "getsentry/*": ["../static/gsApp/*"],
+      "getsentry-images/*": ["../static/images/*"],
+      "admin/*": ["../static/gsAdmin/*"]
     },
 
     "plugins": [