Fix: Completion on last character of embedded language blocks

[idillon-sfl]

Completion was broken on the last character of Python or Bash blocks.

For example, in the following code, if the cursor was on just after the h in ech, the user would see "normal" bitbake completion items instead of bash completion items.

test() {
    ech
}

Completion is still not as responsive as we'd like it to be, especially in Python. I am still looking for a solution.

[WilsonZiweiWang]

On my side, I only have the completion for bash language but everything else seems gone.

[idillon-sfl]

are you sure? For me the Python parts work only once the scan is done, and sometimes it still takes a bit longer to load.

Plus the completion on Python is not very responsive (I hope to find a solution). It appears randomly as I am typing. That being said, I always can trigger it manually with ctrl+space.

Also you will get wrong completion if you type before a function because of this issue: tree-sitter-grammars/tree-sitter-bitbake#16

[deribaucourt]

Works as expected on my end. However, no bash specific completion is suggested if I place my cursor on an empty final newline of a bash function. Which can be addressed separately and is not critical.