Prefer scala-cli pragmas [ci: last-only]

[som-snytt]

Goal is to remove the old header parsing.

Global replace changes range positions in output. (Which also change in a recent PR.)

Conversion of java: and javaVersion: to follow. Edit: uses javaOpt, javacOpt. Edit: also jvm for javaVersion.

Edit: remove old header parsing. Remove one usage of hide: in favor of DirectTest. filter must be quoted if it has embedded spaces.

Follow-up to #10756

[som-snytt]

Missed a few pragmas that were slightly irregular.

One test failure confused me. It's actually testing that multiple pragmas (on different lines) are picked up, but that was broken. However, it happened to exercise the ambiguity between inherited member and def in scope. I guess it's a warning (2.13.14) that is promoted to error if -Xsource;3, but the message text is the same. But the reference is not ambiguous in the sense of erroneous; it's merely confusing.

I'm not sure what I was testing: maybe documenting status quo that "last pragma wins". The companion test shows both options in one pragma (with comma separation). scala-cli appears to accumulate and keep both pragmas, as it errors irrespective of the order of the two pragmas.

➜  scala git:(tweak/test-flags) ✗ skalac -d /tmp/sandbox test/files/neg/using-source3.scala
test/files/neg/using-source3.scala:14: warning: reference to f is ambiguous;
it is both defined in the enclosing class D and inherited in the enclosing class E as method f (defined in class C)
In Scala 2, symbols inherited from a superclass shadow symbols defined in an outer scope.
Such references are ambiguous in Scala 3. To continue using the inherited symbol, write `this.f`.
Or use `-Wconf:msg=legacy-binding:s` to silence this warning. [quickfixable]
    def g = f
            ^
1 warning
➜  scala git:(tweak/test-flags) ✗ skalac -Xsource:3 -d /tmp/sandbox test/files/neg/using-source3.scala
test/files/neg/using-source3.scala:14: error: reference to f is ambiguous;
it is both defined in the enclosing class D and inherited in the enclosing class E as method f (defined in class C)
In Scala 2, symbols inherited from a superclass shadow symbols defined in an outer scope.
Such references are ambiguous in Scala 3. To continue using the inherited symbol, write `this.f`.
Or use `-Wconf:msg=legacy-binding:s` to silence this warning. [quickfixable]
Scala 3 migration messages are issued as errors under -Xsource:3. Use -Wconf or @nowarn to demote them to warnings or suppress.
Applicable -Wconf / @nowarn filters for this fatal warning: msg=<part of the message>, cat=scala3-migration, site=D.E.g
    def g = f
            ^
1 error