- Define a new extension point `configurationDefaults` for contributing default language specific editor settings

This reverts commit 38fbba35.

**bug**
`(` was added as a commit character in 1.9. Combined with `useCodeSnippetsOnMethodSuggest`, this is causing some anoying autocomplete behavior.

**Fix**
Disable `(` as a commit character while `useCodeSnippetsOnMethodSuggest` is enabled.

* Stop TS From Spamming Crash Messages

**Bug**
When the tsserver crashes repeatedly, it can end up spamming users with constant alerts. This is not too helpful

**Fix**
A number of small fixes:

* Lengthen ts 5 crash timeout to 10 seconds from 2 seconds. 5 crashes in 10 seconds == no attempted restart
* Reset the last started time when we have any number of crashes in the row. This resets the crash windows.
* Fix all crashes after 5 retriggering the same logic. I believe the intent was that we should show these errors every five crashes, not on any crash after the fifth one

* Set last startTime on boot

Fixes #7776

**Bug**
Code blocks in the markdown preview are not very good looking

**Fix**
Use default text color for indented code blocks and add a background

Fixes #19856

Fixes #20070

**Bug**
Markdown scroll sync and other sync features do not work for untitled files. The root cause seems to be that the `main.js` markdown file is never loaded

**Fix**
Instead of a using a path without a scheme for `main.js`, use a `file://` path