neovim: move plugin/rustowlsp.lua to lua/rustowlsp.lua

[happy-dude]

The server is currently defined in the plugin directory, which is executed after init.{vim,lua} where everyone usually configures their language servers.

If the plugin is moved from plugin/rustowlsp.lua to lua/rustowlsp.lua then you'd do

require('rustowlsp');
require('lspconfig').rustowlsp.config{}

for configuration.

[cordx56]

Done.
commit hash: c5cd9cd