fix(lsp-inlayhints-nvim): use clangd_extensions.nvim's current repository (dchinmay2)

[MrReasonable]

Refs #1802

📑 Description

lsp-inlayhints-nvim refers to p00f/clangd_extensions.nvim. That plugin's author renamed their GitHub account from p00f to dchinmay2, and the p00f username has since been registered by a different, unrelated account, so the old address only works through GitHub's redirect and could be taken over (repo-jacking). Details and evidence are in #1802.

• lsp/lsp-inlayhints-nvim/init.lua: p00f/clangd_extensions.nvim → dchinmay2/clangd_extensions.nvim

📖 Additional Information

• Not a breaking change: same repository and history, and the lazy.nvim plugin name (clangd_extensions.nvim) is unchanged, so it still merges with the cpp pack's spec and with user overrides.
• Companion to fix(cpp): use clangd_extensions.nvim's current repository (dchinmay2) #1803 (cpp pack) and fix(alabaster): change alabaster.nvim repo owner from p00f to dchinmay2 #1804 (alabaster); split so each PR has a single scope.

[github-actions]

Review Checklist

Does this PR follow the [Contribution Guidelines](development guidelines)? Following is a partial checklist:

Proper conventional commit scoping:

• If you are adding a new plugin, the scope would be the name of the category it is being added into. ex. feat(utility): added noice.nvim plugin

• If you are modifying a pre-existing plugin or pack, the scope would be the name of the plugin folder. ex. fix(noice-nvim): fix LSP handler error

• Pull request title has the appropriate conventional commit type and scope where the scope is the name of the pre-existing directory in the project as described above

• README is properly formatted and uses fenced in links with <url> unless they are inside a [title](url)

• Entry returns a single plugin spec with the new plugin as the only top level spec (not applicable for recipes or packs).

• Proper usage of opts table rather than setting things up with the config function.

• Proper usage of specs table for all specs that are not dependencies of a given plugin (not applicable for recipes or packs).