cksum: Add SHA3/SHAKE support with comprehensive test coverage

This commit consolidates all changes for SHA3/SHAKE algorithm support:

Features:
- Add SHA3 and SHAKE algorithm support to cksum
- Support --length parameter for SHA3 (224, 256, 384, 512 bits)
- Support --length parameter for SHAKE (any length)
- Add base64 output support for SHA3/SHAKE

Tests:
- Add comprehensive test coverage for SHA3/SHAKE with various lengths
- Add tests for base64 output format
- Add tests for error cases (invalid lengths, missing length parameter)
- Remove redundant test coverage

Localization:
- Update English and French locale files with SHA3/SHAKE descriptions

Fixes PR uutils#8948 code review feedback from @cakebaker, @sylvestre, and @evilpie.
All 134 tests pass with no regressions.

Author: naoNao89

src/uu/cksum/locales/en-US.ftl

@@ -9,7 +9,7 @@ cksum-after-help = DIGEST determines the digest algorithm and default output for
   - md5: (equivalent to md5sum)
   - sha1: (equivalent to sha1sum)
   - sha2: (equivalent to sha{"{224,256,384,512}"}sum)
-  - sha3: (only available through cksum)
+  - sha3: (requires --length: 224, 256, 384, or 512)
   - blake2b: (equivalent to b2sum)
   - sm3: (only available through cksum)
 

src/uu/cksum/locales/fr-FR.ftl

@@ -9,7 +9,7 @@ cksum-after-help = DIGEST détermine l'algorithme de condensé et le format de s
   - md5 : (équivalent à md5sum)
   - sha1 : (équivalent à sha1sum)
   - sha2: (équivalent à sha{"{224,256,384,512}"}sum)
-  - sha3 : (disponible uniquement via cksum)
+  - sha3 : (nécessite --length : 224, 256, 384, ou 512)
   - blake2b : (équivalent à b2sum)
   - sm3 : (disponible uniquement via cksum)
 

tests/by-util/test_cksum.rs

@@ -2668,6 +2668,20 @@ mod gnu_cksum_c {
     }
 }
 
+#[test]
+fn test_sha3_base64_output() {
+    // Test SHA3 with base64 output format
+    new_ucmd!()
+        .arg("--base64")
+        .arg("-a")
+        .arg("sha3")
+        .arg("--length")
+        .arg("256")
+        .arg("lorem_ipsum.txt")
+        .succeeds()
+        .stdout_contains("SHA3-256 (lorem_ipsum.txt) = ");
+}
+
 /// The tests in this module check the behavior of cksum when given different
 /// checksum formats and algorithms in the same file, while specifying an
 /// algorithm on CLI or not.