refactor!: change Package API

This changes the following public APIs:

**(_breaking_) Events on the `Package` class**
The `uninstall:success` event on the `Package` class now receives an `InstallReceipt` as argument, instead of an
`InstallHandle`. This receipt is an in-memory representation of what was uninstalled. There's also a new
`uninstall:failed` event for situations where uninstallation for some
reason fails. Note: this also applies to the registry events (i.e.
`package:uninstall:success` and `package:uninstall:failed`).

---

**(_breaking_) `Package:uninstall()` is now asynchronous and receives two new arguments, similarly to `Package:install()`**
While package uninstallations remain synchronous under the hood, the public API has been changed from synchronous ->
asynchronous. Users of this method are recommended to provide a callback in situations where code needs to execute after
uninstallation fully completes.

---

**(_breaking_) `Package:get_install_path()` has been removed.

---

**`Package:install()` now takes an optional callback**
This callback allows consumers to be informed whether installation was successful or not without having to go through a
different, low-level, API. See below for a comparison between the old and new APIs:
```lua
-- before
local handle = pkg:install()
handle:once("closed", function ()
    -- ...
end)

-- after
pkg:install({}, function (success, result)
    -- ...
end)
```

1 files changed, 48 insertions, 0 deletions

diff --git a/lua/mason-core/installer/context/InstallContextCwd.lua b/lua/mason-core/installer/context/InstallContextCwd.lua
new file mode 100644
index 00000000..b365cbd9
--- /dev/null
+++ b/lua/mason-core/installer/context/InstallContextCwd.lua
@@ -0,0 +1,48 @@
+local Result = require "mason-core.result"
+local fs = require "mason-core.fs"
+local path = require "mason-core.path"
+
+---@class InstallContextCwd
+---@field private handle InstallHandle
+---@field private cwd string?
+local InstallContextCwd = {}
+InstallContextCwd.__index = InstallContextCwd
+
+---@param handle InstallHandle
+function InstallContextCwd:new(handle)
+    ---@type InstallContextCwd
+    local instance = {}
+    setmetatable(instance, self)
+    instance.handle = handle
+    instance.cwd = nil
+    return instance
+end
+
+function InstallContextCwd:initialize()
+    return Result.try(function(try)
+        local staging_dir = self.handle.location:staging(self.handle.package.name)
+        if fs.sync.dir_exists(staging_dir) then
+            try(Result.pcall(fs.sync.rmrf, staging_dir))
+        end
+        try(Result.pcall(fs.sync.mkdirp, staging_dir))
+        self:set(staging_dir)
+    end)
+end
+
+function InstallContextCwd:get()
+    assert(self.cwd ~= nil, "Tried to access cwd before it was set.")
+    return self.cwd
+end
+
+---@param new_abs_cwd string
+function InstallContextCwd:set(new_abs_cwd)
+    assert(type(new_abs_cwd) == "string", "new_cwd is not a string")
+    assert(
+        path.is_subdirectory(self.handle.location:get_dir(), new_abs_cwd),
+        ("%q is not a subdirectory of %q"):format(new_abs_cwd, self.handle.location)
+    )
+    self.cwd = new_abs_cwd
+    return self
+end
+
+return InstallContextCwd