Accept 4-5 quotes at end of triple-quoted string

[plajjan]

In triple-quoted strings we accept unescaped quotes inside the string,
for example:

a = """"foo""" # note the 4 " at the start
a = """my dog "foo" ate the cat"""

But it hasn't been supported at the end

a = """foo""""

Because the first three " of the end run of 4 quote chars would be
recognized as the end of the string, leaving a single trailing " that
would result in a syntax error. That has now changed, so we accept 4 or
5 runs of quotes at the end, like so:

a = """foo""""
    ^^^---------- start of quote
       ^^^^------ payload: foo"
           ^^^--- end of quote

a = """foo"""""
    ^^^---------- start of quote
       ^^^^^----- payload: foo""
            ^^^-- end of quote

a = """"foo"""""
    ^^^---------- start of quote
       ^^^^^^---- payload: "foo""
             ^^^- end of quote

There are some preparatory commits first that restructure error handling and improves the flow so that we can propagate hints/notes in structured errors. Many errors from the parser have been converted to such structured errors and now come with Notes / Hints, for example:

ERROR: [error Syntax error]: Expected digits after '.' in format specifier
     ╭──▶ test@1:38-1:38
     │
   1 │ f"Missing precision digits {value:10.}"
     •                                       
     •                                      ╰╸ Expected digits after '.' in format specifier
     •
     │ Hint: Add precision digits, e.g. .2f for 2 decimal places
─────╯

     ╭──▶ test/syntaxerrors/err42.act@1:5-1:6
     │
   1 │ def Z():
     •       
     •     ╰╸ Invalid name 'Z'
     •
     │ Note: Single upper case character (optionally followed by digits) are reserved for type variables
     │ Hint: Use a longer name
─────╯

Fixes #2387