compiler/sem*: better lineinfo for templates (#10428)

* compiler/sem*: better lineinfo for templates

Lineinfo for templates is inconsistant across the compiler, for example:

    doAssert true
    ^        ^

    a[int](10)
    ^^    ^

The `^` marks where the compiler thinks the template starts.

For qualified call, we got the same situation with `proc`s before #10427:

    system.once
          ^

Generics lineinfo within template declaration is also incorrect, for
example, this is where the compiler believes the `T` in `[T]` is:

    template a[T](b: T)
                  ^

This PR addresses all of these problems.

* nimsuggest: add tests for template highlighting

nimsuggest/tests/tgeneric_highlight.nim

@@ -1,8 +1,8 @@
 newSeq[int]()
 system.newSeq[int]()#[!]#
+offsetOf[int]()
 
 discard """
-disabled:true
 $nimsuggest --tester $file
 >highlight $1
 highlight;;skType;;1;;7;;3
@@ -15,4 +15,6 @@ highlight;;skProc;;2;;7;;6
 highlight;;skProc;;2;;7;;6
 highlight;;skType;;2;;14;;3
 highlight;;skProc;;2;;7;;6
+highlight;;skTemplate;;3;;0;;8
+highlight;;skType;;3;;9;;3
 """

nimsuggest/tests/tqualified_highlight.nim

@@ -1,9 +1,12 @@
 system.echo#[!]#
+system.once
 
 discard """
-disabled:true
 $nimsuggest --tester $file
 >highlight $1
 highlight;;skProc;;1;;7;;4
 highlight;;skProc;;1;;7;;4
+highlight;;skTemplate;;2;;7;;4
+highlight;;skTemplate;;2;;7;;4
+highlight;;skTemplate;;2;;7;;4
 """

nimsuggest/tests/ttemplate_highlight.nim

@@ -0,0 +1,9 @@
+doAssert true#[!]#
+
+discard """
+$nimsuggest --tester $1
+>highlight $1
+highlight;;skTemplate;;1;;0;;8
+highlight;;skTemplate;;1;;0;;8
+highlight;;skEnumField;;1;;9;;4
+"""