feat(#256): lint that find not merged bases

[Marat-Tim]

In this pull request, I’m adding a linter that checks whether an object can be merged with its parent. There were two potential approaches to implementing this: one involved identifying full chains of possible merges—for example, in the following code:

<o base=".foo">
  <o base=".bar">
    <o base="x" line="2"/>
  </o>
</o>

These objects could theoretically be merged into:

<o base="x.bar.foo"/>

However, such a search is relatively complex in terms of either memory usage or computational resources

I opted for a simpler approach, where in the above example, the linter will generate a warning like:
Object on line 2 can be merged with its parent

After performing the suggested merge and re-running the linter, another warning will appear, allowing the issue to be resolved over several iterations

[github-actions]

🚀 Performance Analysis

Test	Base Score	PR Score	Change	% Change	Unit	Mode
benchmarks.SourceBench.scansXmir (size=S)	4283.313	4470.818	187.506	4.38%	ms/op	Average Time
benchmarks.SourceBench.scansXmir (size=M)	4945.933	5021.179	75.246	1.52%	ms/op	Average Time
benchmarks.SourceBench.scansXmir (size=L)	5815.847	5830.155	14.308	0.25%	ms/op	Average Time
benchmarks.SourceBench.scansXmir (size=XL)	7252.064	7316.523	64.459	0.89%	ms/op	Average Time
benchmarks.SourceBench.scansXmir (size=XXL)	20143.619	20160.257	16.638	0.08%	ms/op	Average Time

⚠️ Performance loss: benchmarks.SourceBench.scansXmir (size=S) is slower by 187.506 ms/op (4.38%)
⚠️ Performance loss: benchmarks.SourceBench.scansXmir (size=M) is slower by 75.246 ms/op (1.52%)
⚠️ Performance loss: benchmarks.SourceBench.scansXmir (size=L) is slower by 14.308 ms/op (0.25%)
⚠️ Performance loss: benchmarks.SourceBench.scansXmir (size=XL) is slower by 64.459 ms/op (0.89%)
⚠️ Performance loss: benchmarks.SourceBench.scansXmir (size=XXL) is slower by 16.638 ms/op (0.08%)

[Marat-Tim]

@maxonfjvipon

[maxonfjvipon]

@Marat-Tim such example is not correct because .bar method should be taken from some object. So you need to add a nested object that can't be merged with .bar or just remove dot: bar

[Marat-Tim]

@maxonfjvipon I forgot to delete this

[maxonfjvipon]

@Marat-Tim there's something wrong with indentation here

[maxonfjvipon]

@Marat-Tim actually it's pretty good, but I think you missed the one more condition - and not(o). You can add this test:

<o base=".foo">
  <o base="bar">
    <o base="baz"/>
  </o>
</o>

I believe with current approach you'll get a defect, but there's no one

[Marat-Tim]

@maxonfjvipon This is checked with not(text()) because if element has an inner object, text() returns its text content. I added this test

[Marat-Tim]

@yegor256