Push indents to after comments

[alanmcruickshank]

This resolves #4223 . This fix is a little unorthodox - but it works.

When assessing the position of indent effects, we push the effects of any Indent or Dedent segments to after any comment segments. Within a line it shouldn't make a difference, but for end of line comments, it makes sure that any tokens are available in the same IndentPoint that forms the start of the next line. That's the main purpose of what we're doing.

I considered actually moving the Indent and Dedent tokens in the lexing or parsing stage, but that felt like too much "hacking". Keeping this logic in the reflow interpretation code feels acceptable.

[coveralls]

Pull Request Test Coverage Report for Build 3859330151

• 13 of 13 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 3859319340:	0.0%
Covered Lines:	16918
Relevant Lines:	16918

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💛 - Coveralls

[codecov]

Codecov Report

Base: 100.00% // Head: 100.00% // No change to project coverage 👍

Coverage data is based on head (838cae7) compared to base (665e2a2).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #4239   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          200       200           
  Lines        15143     15148    +5     
=========================================
+ Hits         15143     15148    +5     

Impacted Files	Coverage Δ
src/sqlfluff/utils/reflow/reindent.py	100.00% <100.00%> (ø)

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[barrywhart]

In the past, L003 only handled indentation. Any concerns that here it is moving code between lines?

[alanmcruickshank]

I don't think so - this is functionality that is already out in the wild in the treatment of existing hanging indents in 2.0.0a1. All this PR does is fix a bug with it.