Extend MemoryStorage with Tags, Priority, Expire and Sliding modifiers. DROP PHP8.1 Support

[KminekMatej]

• new feature?
• BC break? no
• doc PR: nette/docs Not yet, will do after merge approval

This MR enhances MemoryStorage with ability to index stored items with Tags, Priority, Expiration ts and Sliding.

We are using MemoryStorage during autotests in pipelines to speed up the testing process, but currently we cannot because we highly depend on Tags, Priority etc.

Implementing this feature in MemoryStorage gives us opportunity to speed up the testing process since we could finally replace FileStorage with it.

SInce MemoryStorage is not stored elsewhere then process ram, I dont think it could be considered as BC break.

Tests has been added

[KminekMatej]

I took the liberty to fix also failing pipelines, which (unfortunately) resulted in dropping Php8.1 support due to dropped support of php8.1 in upstream latte/latte repo. Latte changed line comments structure from
/* line X */
to
/* pos X:Y */
in dev-master, which led to failures of this repository tests. However along with that, dropped php8.1 support.

I had two options:

1. Create separate template files for php8.1 test
2. Drop support of Php8.1 completely

SInce Php 8.1 already reached EOL, I decided to drop this support here as well.

Second fixing of pipelines was specifying mandatory extensions in lowest dependencies stage - tests requiring mbstring / tokenizer are now being skipped in this phase