chore(LpSpace): move results about the L^p norm earlier

[YaelDillies]

MeasureTheory.Function.LpSpace is supposed to be about the L^p space itself, but contains a bunch of results about the L^p norm as well. Move those results to MeasureTheory.Function.LpSeminorm.Basic and MeasureTheory.Function.LpSeminorm.CompareExp. Also rename lemmas about nesting of L^p norms.

From LeanAPAP

Moves:

• Memℒp.memℒp_of_exponent_le_of_measure_support_ne_top -> Memℒp.mono_exponent_of_measure_support_ne_top
• Memℒp.memℒp_of_exponent_le -> Memℒp.mono_exponent

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[github-actions]

PR summary d7f05f2544

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

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Declarations diff

+ Memℒp.mono_exponent
+ Memℒp.mono_exponent_of_measure_support_ne_top

You can run this locally as follows

## summary with just the declaration names:
./scripts/declarations_diff.sh <optional_commit>

## more verbose report:
./scripts/declarations_diff.sh long <optional_commit>

The doc-module for script/declarations_diff.sh contains some details about this script.

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Increase in tech debt: (relative, absolute) = (1.00, 0.02)

Current number	Change	Type
60	1	large files

Current commit d7f05f2544
Reference commit 1a9143ba4b

You can run this locally as

./scripts/technical-debt-metrics.sh pr_summary

• The relative value is the weighted sum of the differences with weight given by the inverse of the current value of the statistic.
• The absolute value is the relative value divided by the total sum of the inverses of the current values (i.e. the weighted average of the differences).

[RemyDegenne]

According to the declarations diff automated message, you deleted a bunch of stuff. Can you please restore them?

[YaelDillies]

Those are all the deprecated lemmas dating back from July. I thought it would be pointless moving them around, so I deleted them.

[RemyDegenne]

That's barely 6 months. Let's not delete yet (and when we do, we should do it in a dedicated PR). Please also move the deprecated lemmas.

[YaelDillies]

Here, I've restored the deprecated aliases, but not moved them. I don't want to increase the diff with them, since they are already past the point where they can be deleted (namely one stable release).