Be more consistent about aliases for different subcommands

In some cases we have the same subcommand in multiple places, but it
accepts different aliases in each place. For instance, you can write
either `rustup toolchain uninstall` or `rustup toolchain rm`, but you
can only write `rustup uninstall`, not `rustup rm`.

Add aliases for consistency:
- `rustup add` for `rustup install`, for consistency with
  `rustup toolchain install`.
- `rustup rm` (or "remove" or "delete" or "del") for `rustup uninstall`,
  for consistency with `rustup toolchain uninstall`.
- `rustup self up` for `rustup self update`, for consistency with other
  `update` commands.
- `rustup toolchain up` for `rustup toolchain update`, for consistency
  with other `update` commands.

Author: joshtriplett

src/cli/rustup_mode.rs

@@ -123,14 +123,14 @@ fn plus_toolchain_value_parser(s: &str) -> clap::error::Result<ResolvableToolcha
 #[command(name = "rustup", bin_name = "rustup[EXE]")]
 enum RustupSubcmd {
     /// Install or update the given toolchains, or by default the active toolchain
-    #[command(hide = true, after_help = install_help())]
+    #[command(hide = true, after_help = install_help(), aliases = ["add"])]
     Install {
         #[command(flatten)]
         opts: UpdateOpts,
     },
 
     /// Uninstall the given toolchains
-    #[command(hide = true)]
+    #[command(hide = true, aliases = ["remove", "rm", "delete", "del"])]
     Uninstall {
         #[command(flatten)]
         opts: UninstallOpts,
@@ -332,7 +332,7 @@ enum ToolchainSubcmd {
     },
 
     /// Install or update the given toolchains, or by default the active toolchain
-    #[command(aliases = ["update", "add"], after_help = toolchain_install_help())]
+    #[command(aliases = ["update", "up", "add"], after_help = toolchain_install_help())]
     Install {
         #[command(flatten)]
         opts: UpdateOpts,
@@ -541,6 +541,7 @@ enum OverrideSubcmd {
 )]
 enum SelfSubcmd {
     /// Download and install updates to rustup
+    #[command(alias = "up")]
     Update,
 
     /// Uninstall rustup