refactor!: extract mason-lspconfig to separate plugin (#109)

The rationale behind this is to make boundaries clearer as mason.nvim
has no direct relation with lspconfig per se.

Also, hopefully, by having it as a separate package like this would
encourage more people to write similar extensions (think mason-dap and
mason-null-ls). Ideally such extensions wouldn't be required at all, but
there are definitely gaps to fill as of today.

From now on you'll need to add `williamboman/mason-lspconfig.nvim` as
a plugin if you want to use the `mason-lspconfig` extension:

```lua
use {
    { "williamboman/mason.nvim", branch = "alpha" },
    "williamboman/mason-lspconfig.nvim",
    "neovim/nvim-lspconfig",
}
```

```lua
Plug "williamboman/mason.nvim", { 'branch': 'alpha' }
Plug "williamboman/mason-lspconfig.nvim"
Plug "neovim/nvim-lspconfig"
```

1 files changed, 2 insertions, 6 deletions

diff --git a/Makefile b/Makefile
index 5483a83e..46ab5027 100644
--- a/Makefile
+++ b/Makefile
@@ -2,8 +2,8 @@ INSTALL_ROOT_DIR:=$(shell pwd)/tests/fixtures/mason
 NVIM_HEADLESS:=nvim --headless --noplugin -u tests/minimal_init.vim
 
 dependencies:
+	git clone --depth 1 https://github.com/williamboman/mason-lspconfig.nvim dependencies/pack/vendor/start/mason-lspconfig.nvim
 	git clone --depth 1 https://github.com/nvim-lua/plenary.nvim dependencies/pack/vendor/start/plenary.nvim
-	git clone --depth 1 https://github.com/neovim/nvim-lspconfig dependencies/pack/vendor/start/nvim-lspconfig
 
 .PHONY: clean_dependencies
 clean_dependencies:
@@ -20,16 +20,12 @@ clean: clean_fixtures clean_dependencies
 test: clean_fixtures dependencies
 	INSTALL_ROOT_DIR=${INSTALL_ROOT_DIR} $(NVIM_HEADLESS) -c "call RunTests()"
 
-.PHONY: lspconfig-generate
-lspconfig-generate: dependencies
-	./scripts/nvim.sh scripts/lua/mason-scripts/mason-lspconfig/generate.lua
-
 .PHONY: schemas-generate
 schemas-generate: dependencies
 	./scripts/nvim.sh scripts/lua/mason-scripts/mason-schemas/generate.lua
 
 .PHONY: autogenerate
-autogenerate: schemas-generate lspconfig-generate
+autogenerate: schemas-generate
 
 .PHONY: generate
 generate: dependencies