Release icu_capi 1.5.1 (unicode-org#5123)

unicode-org#5119

Uplift repr(packed) fix to 1.5 (unicode-org#5079)

Uplifts unicode-org#5049 to 1.5.x

Uplift repr(packed) fix to 1.5 (unicode-org#5079)

Uplifts unicode-org#5049 to 1.5.x

Uplift repr(packed) fix to 1.5 (unicode-org#5079)

Uplifts unicode-org#5049 to 1.5.x

Uplift repr(packed) fix to 1.4 (unicode-org#5080)

Uplifts unicode-org#5049 to 1.4.x

Not strictly necessary as per policy, but might be nice to do anyway?

Uplift repr(packed) fix to 1.5 (unicode-org#5079)

Uplifts unicode-org#5049 to 1.5.x

Uplift repr(packed) fix to 1.4 (unicode-org#5080)

Uplifts unicode-org#5049 to 1.4.x

Not strictly necessary as per policy, but might be nice to do anyway?

Uplift repr(packed) fix to 1.5 (unicode-org#5079)

Uplifts unicode-org#5049 to 1.5.x

Enforce C,packed, not just packed, on ULE types (unicode-org#5049)

Fixes unicode-org#5039

Caused by rust-lang/rust#125360. We were
assuming that `packed` meant `C, packed` already. This is an assumption
I've seen throughout the Rust ecosystem so there may be reasons to
revert.

Enforce C,packed, not just packed, on ULE types (unicode-org#5049)

Fixes unicode-org#5039

Caused by rust-lang/rust#125360. We were
assuming that `packed` meant `C, packed` already. This is an assumption
I've seen throughout the Rust ecosystem so there may be reasons to
revert.