borrowck: Implement method translation to BIR

[jdupak]

See: https://github.com:Rust-GCC/gccrs/blob/borrowck-stage2-cleaned/gcc/rust/checks/errors/borrowck/rust-bir-builder-expr-stmt.cc#L263-L263

And implement: https://github.com:Rust-GCC/gccrs/blob/borrowck-stage2-cleaned/gcc/rust/checks/errors/borrowck/rust-bir-builder-expr-stmt.cc#L283-L283

Start from: https://github.com/jdupak/gccrs/tree/borrowck-wip

[jdupak]

@CohenArthur please assign this to @braw-lee

[braw-lee]

yes pls