Bash: Respect `completion-ignore-case` readline setting

[adaszko]

In JIT mode, the current bash completion matching logic simply does completion.starts_with(...) which is wrong when completion-ignore-case is set.

Similarly in AOT mode:

• https://github.com/adaszko/complgen/blob/5e29dcbf46840bd9eb0599dcf737ce786d26340c/src/aot/bash.rs#L127
• https://github.com/adaszko/complgen/blob/5e29dcbf46840bd9eb0599dcf737ce786d26340c/src/aot/bash.rs#L354
• https://github.com/adaszko/complgen/blob/5e29dcbf46840bd9eb0599dcf737ce786d26340c/src/aot/bash.rs#L387
• https://github.com/adaszko/complgen/blob/5e29dcbf46840bd9eb0599dcf737ce786d26340c/src/aot/bash.rs#L408

Fix: Retrieve the settings value with something like bind -V | grep completion-ignore-case and behave conditionally based on its value.

• TODO:
  • [x] Write e2e tests for JIT mode
  • [x] Wrte e2e tests for AOT mode
  • [ ] Fix JIT mode
  • [ ] Fix AOT mode