Support search queries for GHSearchPRs and GHSearchIssues on commandline

[lnzspraj]

Currently, if you use :GHSearchPRs or :GHSearchIssues the functions prompt you for a query in a first step. It would be nice if they supported directly adding the query (such that one could add those to keybindings). For instance a binding only showing currently open PRs would be nice via:

:GHSearchPRs is:open

So in a configuration file one would use

vim.keymap.set('n', '<Leader>ghpo', '<Cmd>GHSearchPRs is:open<CR>', { desc='Search open PRs' })