runtime(java): Improve the recognition of the "style" method declarations

- Request the new regexp engine (v7.3.970) for [:upper:] and
  [:lower:].

- Recognise declarations of in-line annotated methods.

- Recognise declarations of _strictfp_ methods.

- Establish partial order for method modifiers as shown in
  the MethodModifier production; namely, _public_ and
  friends should be written the leftmost, possibly followed
  by _abstract_ or _default_, or possibly followed by other
  modifiers.

- Stop looking for parameterisable primitive types (void<?>,
  int<Object>, etc., are malformed).

- Stop looking for arrays of _void_.

- Acknowledge the prevailing convention for method names to
  begin with a small letter and for class/interface names to
  begin with a capital letter; and, therefore, desist from
  claiming declarations of enum constants and constructors
  with javaFuncDef.
  Rationale:
    + Constructor is distinct from method:
      * its (overloaded) name is not arbitrary;
      * its return type is implicit;
      * its _throws_ clause depends on indirect vagaries of
        instance (variable) initialisers;
      * its invocation makes other constructors of its type
        hierarchy invoked one by one, concluding with the
        primordial constructor;
      * its explicit invocation, via _this_ or _super_, can
        only appear as the first statement in a constructor
        (not anymore, see JEP 447); else, its _super_ call
        cannot appear in constructors of _record_ or _enum_;
        and neither invocation is allowed for the primordial
        constructor;
      * it is not a member of its class, like initialisers,
        and is never inherited;
      * it is never _abstract_ or _native_.
    + Constructor declarations tend to be few in number and
      merit visual recognition from method declarations.
    + Enum constants define a fixed set of type instances
      and more resemble class variable initialisers.

Note that the code duplicated for @javaFuncParams is written
keeping in mind for g:java_highlight_functions a pending 3rd
variant, which would require none of the :syn-cluster added
groups.

closes: #14620

Signed-off-by: Aliaksei Budavei <0x000c70@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/syntax/testdir/dumps/java_methods_style_00.dump

@@ -0,0 +1,20 @@
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+@75
+@75
+|i+0#e000e06&|m|p|o|r|t| +0#0000000&|j|a|v|a|.|l|a|n|g|.|a|n@1|o|t|a|t|i|o|n|.|T|a|r|g|e|t|;| @39
+@75
+|a+0#4040ff13&|b|s|t|r|a|c|t| +0#0000000&|c+0#00e0003&|l|a|s@1| +0#0000000&|S|t|y|l|e|M|e|t|h|o|d|s|T|e|s|t|s| @42
+|{+0#00e0e07&| +0#0000000&@73
+@4|p+0#00e0003&|r|o|t|e|c|t|e|d| +0#0000000&|S|t|y|l|e|M|e|t|h|o|d|s|T|e|s|t|s|(|)| |{+0#00e0e07&| +0#0000000&|}+0#00e0e07&| +0#0000000&@37
+@75
+@4|r+0#00e0003&|e|c|o|r|d| +0#0000000&|Τ|ʬ|<|α|>|(|α| |a|)| |{+0#00e0e07&| +0#0000000&|}+0#00e0e07&| +0#0000000&@49
+@75
+@4|e+0#00e0003&|n|u|m| +0#0000000&|𝓔| @64
+@4|{+0#00e0e07&| +0#0000000&@69
+@8|A|(|"+0#e000002&|𝕬|"|)+0#0000000&|,| |B|(|"+0#e000002&|𝕭|"|)+0#0000000&|,| |C|(|"+0#e000002&|𝕮|"|)+0#0000000&|,| |D|(|"+0#e000002&|𝕯|"|)+0#0000000&|,| @35
+@8|E|(|"+0#e000002&|𝕰|"|)+0#0000000&|,| |F|(|"+0#e000002&|𝕱|"|)+0#0000000&|,| |G|(|"+0#e000002&|𝕲|"|)+0#0000000&|,| |H|(|"+0#e000002&|𝕳|"|)+0#0000000&|;| @35
+@8|f+0#4040ff13&|i|n|a|l| +0#0000000&|S|t|r|i|n|g| |𝐬|;| @51
+@8|p+0#00e0003&|r|i|v|a|t|e| +0#0000000&|𝓔|(|S|t|r|i|n|g| |𝐬|)| |{+0#00e0e07&| +0#0000000&|t+0#00e0003&|h|i|s|.+0#0000000&|𝐬| |=| |𝐬|;| |}+0#00e0e07&| +0#0000000&@31
+@4|}+0#00e0e07&| +0#0000000&@69
+@75
+@57|1|,|1| @10|T|o|p|