Rename random decimal to random float (#10320)

# Description
Similar to #9979

# User-Facing Changes
`random decimal` will now raise a warning and can be removed in an
upcoming release.

New command is named `random float`

# Tests + Formatting
Tests updated and improved.

crates/nu-command/tests/commands/random/float.rs

@@ -0,0 +1,26 @@
+use nu_test_support::nu;
+
+#[test]
+fn generates_a_float() {
+    let actual = nu!("random float 42..43");
+
+    // Attention: this relies on the string output
+    assert!(actual.out.starts_with("42") || actual.out.starts_with("43"));
+    let actual = nu!("random float 42..43 | describe");
+
+    assert_eq!(actual.out, "float")
+}
+
+#[test]
+fn generates_55() {
+    let actual = nu!("random float 55..55");
+
+    assert!(actual.out.contains("55"));
+}
+
+#[test]
+fn generates_0() {
+    let actual = nu!("random float ..<1");
+
+    assert!(actual.out.contains('0'));
+}