encode/decode for multiple alphabets (#13428)

Based on the discussion in #13419.


## Description

Reworks the `decode`/`encode` commands by adding/changing the following
bases:

- `base32`
- `base32hex`
- `hex`
- `new-base64`

The `hex` base is compatible with the previous version of `hex` out of
the box (it only adds more flags). `base64` isn't, so the PR adds a new
version and deprecates the old one.

All commands have `string -> binary` signature for decoding and `string
| binary -> string` signature for encoding. A few `base64` encodings,
which are not a part of the
[RFC4648](https://datatracker.ietf.org/doc/html/rfc4648#section-6), have
been dropped.


## Example usage

```Nushell
~/fork/nushell> "string" | encode base32 | decode base32 | decode
string
```

```Nushell
~/fork/nushell> "ORSXG5A=" | decode base32
# `decode` always returns a binary value
Length: 4 (0x4) bytes | printable whitespace ascii_other non_ascii
00000000:   74 65 73 74                                          test
```


## User-Facing Changes

- New commands: `encode/decode base32/base32hex`.
- `encode hex` gets a `--lower` flag.
- `encode/decode base64` deprecated in favor of `encode/decode
new-base64`.

crates/nu-command/src/strings/encode_decode/decode_base64.rs

@@ -1,10 +1,11 @@
 use super::base64::{operate, ActionType, Base64CommandArguments, CHARACTER_SET_DESC};
 use nu_engine::command_prelude::*;
+use nu_protocol::{report_warning_new, ParseWarning};
 
 #[derive(Clone)]
-pub struct DecodeBase64;
+pub struct DecodeBase64Old;
 
-impl Command for DecodeBase64 {
+impl Command for DecodeBase64Old {
     fn name(&self) -> &str {
         "decode base64"
     }
@@ -77,6 +78,16 @@ impl Command for DecodeBase64 {
         call: &Call,
         input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
+        report_warning_new(
+            engine_state,
+            &ParseWarning::DeprecatedWarning {
+                old_command: "decode base64".into(),
+                new_suggestion: "the new `decode new-base64` version".into(),
+                span: call.head,
+                url: "`help decode new-base64`".into(),
+            },
+        );
+
         let character_set: Option<Spanned<String>> =
             call.get_flag(engine_state, stack, "character-set")?;
         let binary = call.has_flag(engine_state, stack, "binary")?;
@@ -114,6 +125,6 @@ mod tests {
 
     #[test]
     fn test_examples() {
-        crate::test_examples(DecodeBase64)
+        crate::test_examples(DecodeBase64Old)
     }
 }

crates/nu-command/src/strings/encode_decode/encode_base64.rs

@@ -1,10 +1,11 @@
 use super::base64::{operate, ActionType, Base64CommandArguments, CHARACTER_SET_DESC};
 use nu_engine::command_prelude::*;
+use nu_protocol::{report_warning_new, ParseWarning};
 
 #[derive(Clone)]
-pub struct EncodeBase64;
+pub struct EncodeBase64Old;
 
-impl Command for EncodeBase64 {
+impl Command for EncodeBase64Old {
     fn name(&self) -> &str {
         "encode base64"
     }
@@ -81,6 +82,16 @@ impl Command for EncodeBase64 {
         call: &Call,
         input: PipelineData,
     ) -> Result<PipelineData, ShellError> {
+        report_warning_new(
+            engine_state,
+            &ParseWarning::DeprecatedWarning {
+                old_command: "encode base64".into(),
+                new_suggestion: "the new `encode new-base64` version".into(),
+                span: call.head,
+                url: "`help encode new-base64`".into(),
+            },
+        );
+
         let character_set: Option<Spanned<String>> =
             call.get_flag(engine_state, stack, "character-set")?;
         let binary = call.has_flag(engine_state, stack, "binary")?;
@@ -118,6 +129,6 @@ mod tests {
 
     #[test]
     fn test_examples() {
-        crate::test_examples(EncodeBase64)
+        crate::test_examples(EncodeBase64Old)
     }
 }

crates/nu-command/src/strings/encode_decode/mod.rs

@@ -6,6 +6,6 @@ mod encode_base64;
 mod encoding;
 
 pub use self::decode::Decode;
-pub use self::decode_base64::DecodeBase64;
+pub use self::decode_base64::DecodeBase64Old;
 pub use self::encode::Encode;
-pub use self::encode_base64::EncodeBase64;
+pub use self::encode_base64::EncodeBase64Old;