Enables the new `@` block syntax by default by removing the `enabledBlockTypes` flags. There are still some internal flags that allow special use cases to opt out of the block syntax, like during XML parsing and when compiling older libraries (see #51979).
PR Close#51994
* Updates two of the md files to prioritize standalone components/architecture
* Updates three examples referenced in the guides
* Updates the svg diagram to reference the EnvironmentInjector instead of the ModuleInjector
PR Close#51572
