refactor!: consolidate Lua registry sources and the Package API (#1498)

**This removes the following APIs:**
- `Package:check_new_version()`. Instead use the new `Package:get_latest_version()`.

**This has a breaking change in the following APIs:**
- `Package:get_installed_version()` now no longer takes a callback but instead returns the installed version or `nil` if
  not installed.

<details>
<summary>To handle these breaking changes in plugins, leverage the `mason.version` module, for example:</summary>

```lua
local mason_version = require("mason.version")
local registry = require("mason-registry")
local pkg = registry.get_package("rust-analyzer")

if mason_version.MAJOR_VERSION < 2 then
    -- before
    pkg:check_new_version(function (success, new_version)
        -- …
    end)
    pkg:get_installed_version(function (success, installed_version)
        -- …
    end)
else
    -- after
    local new_version = pkg:get_latest_version()
    local installed_version = pkg:get_installed_version()
fi
```

</details>

---

<details>
<summary>This change also introduces breaking changes for Lua registry sources, by consolidating the package schema with the
registry.</summary>

The following is an example of a package defined in a Lua registry, following the new schema:

```lua
local Pkg = require("mason-core.package")

return Pkg.new {
    schema = "registry+v1",
    name = "ripgrep",
    description = "ripgrep recursively searches directories for a regex pattern while respecting your gitignore.",
    homepage = "https://github.com/BurntSushi/ripgrep",
    licenses = { Pkg.License.MIT },
    languages = {},
    categories = {},
    source = {
        id = "pkg:mason/ripgrep@13.0.0",
        ---@param ctx InstallContext
        ---@param purl Purl
        install = function(ctx, purl)
            -- Arbitrary installation code.
        end,
    },
    bin = {
        rg = "./bin/rg",
    },
}
```

</details>

1 files changed, 4 insertions, 3 deletions

diff --git a/lua/mason-registry/sources/util.lua b/lua/mason-registry/sources/util.lua
index 262cbef2..80d5f16f 100644
--- a/lua/mason-registry/sources/util.lua
+++ b/lua/mason-registry/sources/util.lua
@@ -15,18 +15,19 @@ function M.map_registry_spec(spec)
         return Optional.empty()
     end
 
-    -- XXX: this is for compatibilty with the PackageSpec structure
-    spec.desc = spec.description
     return Optional.of(spec)
 end
 
 ---@param buffer table<string, Package>
 ---@param spec RegistryPackageSpec
 M.hydrate_package = _.curryN(function(buffer, spec)
-    -- hydrate Pkg.Lang index
+    -- hydrate Pkg.Lang/License index
     _.each(function(lang)
         local _ = Pkg.Lang[lang]
     end, spec.languages)
+    _.each(function(lang)
+        local _ = Pkg.License[lang]
+    end, spec.licenses)
 
     local pkg = buffer[spec.name]
     if pkg then