simplify naming, move grammar to subpackage

build.gradle.kts

src/main/grammar/Aspect.bnf

src/main/grammar/Aspect.flex

src/main/grammar/Grammar.bnf

src/main/grammar/Grammar.flex

src/main/grammar/JastAddAspect.flex

src/main/java/org/jastadd/tooling/RelAstGrammar.java

src/main/java/org/jastadd/tooling/aspect/Aspect.java

src/main/java/org/jastadd/tooling/aspect/AspectFileType.java

...in/java/org/jastadd/tooling/aspect/AttributeFileType.java

...ava/org/jastadd/tooling/aspect/JastAddAspectLanguage.java

.../org/jastadd/tooling/aspect/lexer/AspectLexerAdapter.java

...jastadd/tooling/aspect/parser/AspectParserDefinition.java

...ava/org/jastadd/tooling/aspect/psi/AspectElementType.java

src/main/java/org/jastadd/tooling/aspect/psi/AspectFile.java

.../java/org/jastadd/tooling/aspect/psi/AspectTokenType.java

src/main/java/org/jastadd/tooling/grammar/Grammar.java

...in/java/org/jastadd/tooling/grammar/GrammarAnnotator.java

src/main/java/org/jastadd/tooling/grammar/GrammarBlock.java

...stadd/tooling/grammar/GrammarChooseByNameContributor.java