--filenames:abs|canonical|legacyRelProj for filenames in compiler msgs (replaces --listfullpaths:on|off)

[timotheecour]

• introduces --filenames:abs|canonical|legacyRelProj for filenames in compiler msgs (replaces --listfullpaths:on|off which is kept for backward compatibility)
  --filenames:abs is same as the old --listfullpaths:on
  --filenames:legacyRelProj is the same as the old --listfullpaths:off
  --filenames:canonical reuses the code from fix #16973 ; nim doc now shows correct, canonical import name in title #16999
  --listfullpaths:off is now mapped to --filenames:canonical (but i could change it to --filenames:legacyRelProj if needed)

• supersedes and closes [superseded] --listFullPaths:off now shows paths relative to cwd #13058, it'll be very easy to add --filenames:relative after this PR if needed

• --filenames:canonical is more context-independent, stable (independent of where nimble packages are installed) and less surprising than --filenames:legacyRelProj which was sometimes showing relative paths wrt main project name, sometimes show ../ in path, and sometimes show absolute paths

example 1

when true:
  import compiler/options
  var a: ConfigRef2

--filenames:canonical

tests/nim/all/t12177.nim(21, 10) Error: undeclared identifier: 'ConfigRef2'
candidates (edit distance, scope distance); see '--spellSuggest':
 (1, 2): 'ConfigRef' [type declared in compiler/options.nim(268, 3)]
    var a: ConfigRef2

--filenames:legacyRelProj

t12177.nim(21, 10) Error: undeclared identifier: 'ConfigRef2'
candidates (edit distance, scope distance); see '--spellSuggest':
 (1, 2): 'ConfigRef' [type declared in /Users/timothee/git_clone/nim/Nim_prs/compiler/options.nim(268, 3)]
    var a: ConfigRef2

=> as you can see the relative vs absolute paths with --filenames:legacyRelProj (old --listfullpaths:off)are non-intuitive

example 2

with a nimble package

when true:
  import pkg/regex
  var a = re(12)

nim r --filenames:canonical /pathto/tests/nim/all/t12177.nim

tests/nim/all/t12177.nim(17, 13) Error: type mismatch: got <int literal(12)>
but expected one of:
func re(s: static string): static[Regex] [func declared in regex.nim(289, 8)]
  first type mismatch at position: 1
  required type for s: static[string] [static declared in regex.nim(290, 5)]
  but expression '12' is of type: int literal(12) [int declared in system/basic_types.nim(2, 3)]
...

note

• for files that aren't rooted inside a nimble package, it just shows the file name (lastPathPart), as is also case in docs since fix #16973 ; nim doc now shows correct, canonical import name in title #16999; that's the simplest but other options are reasonable

future work

• declaredlocs has a minor bug: static (and typedesc and ...?) should be skipped:
  required type for s: static[string] [static declared in regex(290, 5)]
  =>
  required type for s: static[string] [string declared in system(34, 3)]
  EDIT => PR --declaredlocs now shows location for T instead of static in proc fn(a: static T) #17795

• (pre-existing issue) honor conf.filenameOption for --hint:msgorigin (right now hardcoded to absolute paths because of toFileLineCol(InstantiationInfo)) (see also MsgOrigin doesn't honor listfullpaths:off timotheecour/Nim#463)

• maybe prefix nimble packages (other than one from main project file) with pkg/ for clarity