Add feature no-allocator to ink_allocator

[kvinwang]

Fixes #1414

[codecov-commenter]

Codecov Report

Merging #1415 (55fc77a) into master (69f959f) will increase coverage by 6.07%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1415      +/-   ##
==========================================
+ Coverage   65.92%   71.99%   +6.07%     
==========================================
  Files         187      187              
  Lines        5951     5953       +2     
==========================================
+ Hits         3923     4286     +363     
+ Misses       2028     1667     -361     

Impacted Files	Coverage Δ
crates/allocator/src/bump.rs	85.95% <0.00%> (-1.45%)	⬇️
crates/ink/ir/src/ir/attrs.rs	82.27% <0.00%> (+3.60%)	⬆️
crates/ink/ir/src/ir/item_impl/callable.rs	91.91% <0.00%> (+4.04%)	⬆️
crates/ink/ir/src/ir/trait_def/item/mod.rs	90.16% <0.00%> (+4.91%)	⬆️
crates/ink/ir/src/ir/item_impl/constructor.rs	93.84% <0.00%> (+6.15%)	⬆️
crates/ink/ir/src/ir/selector.rs	88.00% <0.00%> (+8.00%)	⬆️
crates/ink/ir/src/ir/idents_lint.rs	71.42% <0.00%> (+9.52%)	⬆️
crates/ink/ir/src/ir/item_impl/message.rs	92.13% <0.00%> (+14.60%)	⬆️
crates/ink/ir/src/ir/item/mod.rs	60.71% <0.00%> (+16.66%)	⬆️
crates/ink/ir/src/ir/item_impl/impl_item.rs	57.44% <0.00%> (+17.02%)	⬆️
... and 15 more

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[tolak]

I was trying to use some types from substrate FRAME, which will lead to a global_allocator conflict with the one used ink, that makes me think about should we need an approach to enable/disable the global_allocator like this.