add `feat_` cfg aliases #7994

Job	Run time
L10n/Locale Support Verification	8m 4s
L10n/Locale Embedding - Cat Utility	1m 21s
L10n/Embedded Locale Regression Test	2m 1s
L10n/Fluent Syntax Check	19s
L10n/Installation Test (Make & Cargo) (ubuntu-latest, feat_os_unix)	31s
L10n/Multi-call Binary Install Test (macos-latest, feat_os_macos)	6m 54s
L10n/Build and Test (ubuntu-latest, feat_os_unix)	4m 35s
L10n/Installation Test (Make & Cargo) (macos-latest, feat_os_macos)	10m 50s
L10n/Clap Error Localization Test	1m 42s
L10n/Multi-call Binary Install Test (ubuntu-latest, feat_os_unix)	4m 55s
L10n/Build and Test (windows-latest, feat_os_windows)	8m 53s
L10n/Build and Test (macos-latest, feat_os_macos)	3m 33s
L10n/Locale Embedding - Ls Utility	58s
L10n/Locale Embedding - Multicall Binary	2m 14s
L10n/Locale Embedding - Cargo Install	1m 2s
L10n/French Integration Test	2m 2s
L10n/Locale Embedding Regression Test	2s
	59m 56s

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