fix: remove and ignore Eclipse JDT language server files

[c-dilks]

Ignore and remove dotfiles from jdtls (https://github.com/eclipse-jdtls/eclipse.jdt.ls)

[c-dilks]

Although these may be useful to have,

• not everyone uses this LSP
• the dot files aren't provided for all modules
• they typically get regenerated, e.g., by an IDE that uses jdtls
• they may fall out of date

If we really want these, make a pre-commit hook...