Fixes #90197: Set each individual character width if the whitespace rendering character has a different width than space

Fixes #87359: Use U+2E31 - WORD SEPARATOR MIDDLE DOT instead of U+00B7 - MIDDLE DOT when the latter is wider than space

Readonly helps with type guards and code comprehension

Const is preferred for type guards

In these cases, the programmer has explicitly indicated that the type should be nullable

We compile using the alwaysStrict flag so these directives are not needed

This part removes most `use strict` directives that are right after the file header

This reverts commit 3a3f0e41.

See #36760