Move ink_lang_macro UI tests into macro-specific folders

[Robbepop]

Carved out refactoring work from #665 to shrink its diff.

[codecov-commenter]

Codecov Report

Merging #934 (bc145f1) into master (41b0a1c) will increase coverage by 1.97%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #934      +/-   ##
==========================================
+ Coverage   84.20%   86.18%   +1.97%     
==========================================
  Files         173      171       -2     
  Lines        7939     7656     -283     
==========================================
- Hits         6685     6598      -87     
+ Misses       1254     1058     -196     

Impacted Files	Coverage Δ
...g/macro/tests/ui/contract/pass/01-noop-contract.rs	16.66% <ø> (ø)
...acro/tests/ui/contract/pass/02-flipper-contract.rs	8.33% <ø> (ø)
.../tests/ui/contract/pass/03-incrementer-contract.rs	5.00% <ø> (ø)
.../macro/tests/ui/contract/pass/04-erc20-contract.rs	1.47% <ø> (ø)
...macro/tests/ui/contract/pass/05-erc721-contract.rs	0.58% <ø> (ø)
...g/macro/tests/ui/contract/pass/06-non-ink-items.rs	16.66% <ø> (ø)
...tests/ui/contract/pass/07-flipper-as-dependency.rs	100.00% <ø> (ø)
...ui/contract/pass/08-flipper-as-dependency-trait.rs	100.00% <ø> (ø)
...lang/macro/tests/ui/contract/pass/09-static-env.rs	12.50% <ø> (ø)
...ro/tests/ui/contract/pass/10-derive-for-storage.rs	16.66% <ø> (ø)
... and 27 more

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