Fix/improve handling of forward declarations in nimsuggest (#20493)

* Fix/improve handling of forward declarations in nimsuggest

- ideUse now works fine when invoked on the implementation
- implemented ideDeclaration to make cover lsp feature textDocument/declaration
- fixed performance issue related to deduplicating symbols. Now the
deduplication happens after the symbols are filtered. As a alternative we might
change the way cached symbols are stored(e. g. use set).
- I also fixed the way globalSymbols work. Now it will sort the responses based
on the match location to make sure that the results are sorted in user friendly way.

* Update nimsuggest/nimsuggest.nim

Co-authored-by: Andreas Rumpf <rumpf_a@web.de>

Co-authored-by: Andreas Rumpf <rumpf_a@web.de>

nimsuggest/tests/tv3_forward_definition.nim

@@ -0,0 +1,23 @@
+proc de#[!]#mo(): int
+
+proc de#[!]#mo(): int = 5
+
+let a = de#[!]#mo()
+
+discard """
+$nimsuggest --v3 --tester $file
+>use $1
+use	skProc	tv3_forward_definition.demo	proc (): int{.noSideEffect, gcsafe, locks: 0.}	$file	1	5	""	100
+def	skProc	tv3_forward_definition.demo	proc (): int{.noSideEffect, gcsafe, locks: 0.}	$file	3	5	""	100
+use	skProc	tv3_forward_definition.demo	proc (): int{.noSideEffect, gcsafe, locks: 0.}	$file	5	8	""	100
+>use $2
+use	skProc	tv3_forward_definition.demo	proc (): int{.noSideEffect, gcsafe, locks: 0.}	$file	1	5	""	100
+def	skProc	tv3_forward_definition.demo	proc (): int{.noSideEffect, gcsafe, locks: 0.}	$file	3	5	""	100
+use	skProc	tv3_forward_definition.demo	proc (): int{.noSideEffect, gcsafe, locks: 0.}	$file	5	8	""	100
+>declaration $1
+declaration	skProc	tv3_forward_definition.demo	proc (): int{.noSideEffect, gcsafe, locks: 0.}	$file	3	5	""	100
+>declaration $2
+declaration	skProc	tv3_forward_definition.demo	proc (): int{.noSideEffect, gcsafe, locks: 0.}	$file	1	5	""	100
+>declaration $3
+declaration	skProc	tv3_forward_definition.demo	proc (): int{.noSideEffect, gcsafe, locks: 0.}	$file	1	5	""	100
+"""

nimsuggest/tests/tv3_globalSymbols.nim

@@ -0,0 +1,14 @@
+# Tests the order of the matches
+proc Btoken(): int = 5
+proc tokenA(): int = 5
+proc token(): int = 5
+proc BBtokenA(): int = 5
+
+discard """
+$nimsuggest --v3 --tester $file
+>globalSymbols token
+def	skProc	tv3_globalSymbols.token	proc (): int{.noSideEffect, gcsafe, locks: 0.}	$file	4	5	""	100
+def	skProc	tv3_globalSymbols.tokenA	proc (): int{.noSideEffect, gcsafe, locks: 0.}	$file	3	5	""	100
+def	skProc	tv3_globalSymbols.Btoken	proc (): int{.noSideEffect, gcsafe, locks: 0.}	$file	2	5	""	100
+def	skProc	tv3_globalSymbols.BBtokenA	proc (): int{.noSideEffect, gcsafe, locks: 0.}	$file	5	5	""	100
+"""