Support pwsh format for show-env export #2919

Job	Run time
test (1.81)	1m 57s
test-llvm (14)	1m 51s
test (stable)	1m 59s
test-llvm (15)	1m 48s
test (beta)	1m 52s
test-llvm (16)	1m 56s
test (nightly)	2m 39s
test-llvm (17)	1m 57s
test (nightly, macos-latest)	3m 4s
test-llvm (18)	1m 13s
test (nightly, windows-latest)	4m 31s
msrv / prepare	6s
test-llvm (19)	1m 15s
deny / deny	16s
miri / miri	2m 12s
release-dry-run / prepare	6s
tidy / tidy	1m 6s
msrv / build (ubuntu-latest)	1m 43s
msrv / build (windows-latest)	2m 17s
release-dry-run / build (aarch64-unknown-linux-gnu)	1m 44s
release-dry-run / build (aarch64-unknown-linux-musl)	1m 18s
release-dry-run / build (aarch64-apple-darwin, macos-13)	3m 15s
release-dry-run / build (x86_64-unknown-linux-gnu)	1m 6s
release-dry-run / build (x86_64-unknown-linux-musl)	1m 21s
release-dry-run / build (x86_64-apple-darwin, macos-13)	1m 56s
release-dry-run / build (x86_64-pc-windows-msvc, windows-2019)	2m 23s
release-dry-run / build (x86_64-unknown-freebsd)	1m 51s
release-dry-run / build (universal-apple-darwin, macos-13)	4m 54s
	53m 36s

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