feature #52079 [HttpKernel] Add parameters kernel.runtime_mode and …

…`kernel.runtime_mode.*`, all set from env var `APP_RUNTIME_MODE` (nicolas-grekas)

This PR was merged into the 6.4 branch.

Discussion
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[HttpKernel] Add parameters `kernel.runtime_mode` and `kernel.runtime_mode.*`, all set from env var `APP_RUNTIME_MODE`

| Q             | A
| ------------- | ---
| Branch?       | 6.4
| Bug fix?      | no
| New feature?  | yes
| Deprecations? | no
| Tickets       | Fix #51340
| License       | MIT
| Doc PR        | TODO

Alternative to #51408. I think this approach is simpler and more powerful.

Here, we ensure that the kernel always provides a new `kernel.runtime_mode` parameter. This parameter is an array derived by default from the `APP_RUNTIME_MODE` env var, using the `query_string` processor.

This also creates 3 new parameters that should be the most common: `kernel.runtime_mode.web`, `kernel.runtime_mode.cli`, and `kernel.runtime_mode.worker`.

A long-running server would typically set `APP_RUNTIME_MODE` to `web=1&worker=1` or `web=0&worker=1` when appropriate (eg https://github.com/php-runtime/frankenphp-symfony/ should do so when `FRANKENPHP_WORKER` is set.)

I screened the codebase and updated them all except cache pools (where the SAPI is used to enable/disable locking) and error renderers (where the SAPI is used to turn html-rendering on/off.) These require more work that could be done later on. There are a few other remaining usages of `PHP_SAPI` but these look not appropriate for the new flag.

Commits
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7c70aec37ad [HttpKernel] Add parameters `kernel.runtime_mode` and `kernel.runtime_mode.*`, all set from env var `APP_RUNTIME_MODE`

Loader/PhpFileLoader.php

@@ -22,7 +22,7 @@ class PhpFileLoader extends FileLoader
 
     protected function loadResource(string $resource): array
     {
-        if ([] === self::$cache && \function_exists('opcache_invalidate') && filter_var(\ini_get('opcache.enable'), \FILTER_VALIDATE_BOOL) && (!\in_array(\PHP_SAPI, ['cli', 'phpdbg'], true) || filter_var(\ini_get('opcache.enable_cli'), \FILTER_VALIDATE_BOOL))) {
+        if ([] === self::$cache && \function_exists('opcache_invalidate') && filter_var(\ini_get('opcache.enable'), \FILTER_VALIDATE_BOOL) && (!\in_array(\PHP_SAPI, ['cli', 'phpdbg', 'embed'], true) || filter_var(\ini_get('opcache.enable_cli'), \FILTER_VALIDATE_BOOL))) {
             self::$cache = null;
         }