fix notes crashing and leaking single comments notes

[vidit-od]

This PR fixes :

1. Issue hls-notes-plugin crashes instead of reporting no locations #4763
2. Leaking Single Comment Notes Declaration

here the definatination declaration is :

[fendor]

Leaking Single Comment Notes Declaration

What does this mean?

[vidit-od]

My bad, i did not do a good job explaining the issue :

There are 2 ways to do Note Declaration
1 ) multi line comments ( or Block Note)
2 ) single line comments ( or Line Note ) Example below :

The Note ending condition for 2nd type of declaration was not defined properly. Hence the content outside it was also picked up as content. Below image has {- Note [Not a valid note] which should not be there in hover.

To Prevent this we have to Define proper ending conditions, which are different for both the types on Notes. Hence in the above implementation we first check the type of note declaration and extract content accordingly !

[fendor]

LGTM, thank you!

Waiting for @jvanbruegge to review as well

[jvanbruegge]

Aside from @fendor's small nit LGTM

[vidit-od]

Done !!
Thank you for reviewing this PR.