fix(mason): migrate to mason v2 (#6053)

## Description
`mason-lspconfig` v2 made changes to conform with latest Neovim
`vim.lsp.config`/`vim.lsp.enable` API.

- Lock `mason` and `mason-lspconfig` to v1 versions for Neovim <0.11 and
latest HEAD for Neovim >=0.11.
- Change `:get_install_path()` method in LazyVim to use
`LazyVim.get_pkg_path()` and also update name references to new ones.
- Change `nvim-lspconfig` from `LazyFile` to `{ "BufReadPre",
"BufNewFile", "BufWritePre" }` for Neovim >=0.11, since on `BufReadPost`
the LSP would not attach on the first buffer. Previously the
`setup.handlers()` function from `mason-lspconfig` would take care of
that, but that has been removed on v2. I fail to think if there's a
better way to handle this.

Most of the changes in `/lsp/init.lua` are thanks to @williamboman
comment
[here](https://github.com/LazyVim/LazyVim/pull/6041#issuecomment-2857266471).

I've also seen that both `mason-lspconfig` and `rustaceanvim` now have
as minimum requirements Neovim >=0.11.
As such I would suggest, instead of all the conditional checks for
Neovim versions to create a stable release where we pin `mason` and
`mason-lspconfig` to v1 versions and then only incorporate William's
suggestions in a new release and mention in the README that users who
are on Neovim <0.11 should use the stable release where the plugin
versions are pinned to v1. Not sure how you want to tackle this, so this
is merely just a suggestion from my part.

Both #6041 and #6045 tackle only with the new name references and the
offending line that was causing the error, but don't take into
consideration the LSP servers configurations. `opts.setup` would not
execute on both, since that was handled by `setup_handlers()` function
in the past. I checked with Typescript lang and with those PRs there are
no Javascript settings in `vtsls` (by checking with
`:=LazyVim.opts("nvim-lspconfig").servers.vtsls`).
#6045 also tried to change the method `:get_install_pkg()` by using
`vim.fn.exepath`, but to my understanding that only returns the binary
path not the package installation path and that is later concatenated to
find other paths, which I believe is not correct.

PS: There are 2 commits, because my LazyVim fork was not up to date and
updated it and then merged the branch I had into a new branch. Sorry if
that causes any inconvenience.
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## Related Issue(s)
Fixes #6039
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  If this PR fixes any issues, please link to the issue here.
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## Screenshots

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## Checklist

- [x] I've read the
[CONTRIBUTING](https://github.com/LazyVim/LazyVim/blob/main/CONTRIBUTING.md)
guidelines.

---------

Co-authored-by: Folke Lemaitre <folke.lemaitre@gmail.com>
Co-authored-by: William Boman <william@redwill.se>
Co-authored-by: Luis Durão <kpvrzlzzx@mozmail.com>

tests/extras/extra_spec.lua

@@ -26,7 +26,8 @@ describe("Extra", function()
     return not vim.tbl_contains(ignore, extra.modname)
   end, extras)
 
-  local lsp_to_pkg = require("mason-lspconfig.mappings.server").lspconfig_to_package
+  local lsp_to_pkg = {}
+  lsp_to_pkg = require("mason-lspconfig.mappings").get_mason_map().lspconfig_to_package
 
   local tsspec = Plugin.Spec.new({
     import = "lazyvim.plugins.treesitter",

tests/minit.lua

@@ -9,8 +9,8 @@ require("lazy.minit").setup({
     { dir = vim.uv.cwd() },
     { "LazyVim/starter" },
     { "nvim-treesitter/nvim-treesitter" },
-    { "mason-org/mason-lspconfig.nvim", version = "^1.0.0" },
-    { "mason-org/mason.nvim", version = "^1.0.0" },
+    { "mason-org/mason-lspconfig.nvim" },
+    { "mason-org/mason.nvim" },
     { "nvim-mini/mini.icons", opts = {} },
   },
 })