[llvm] [RISCV] Add codegen patterns to support short forward branches with immediates (PR #185643)

[via llvm-commits]

hchandel wrote:

I tried organizing the test cases into 12 separate files, where each file contains all the test cases for a single `Xqcibi` instruction. In each test file, test cases for all instructions currently supported in short forward branch are present. Is this way acceptable or there is some better way?

https://github.com/llvm/llvm-project/pull/185643