feat: slice, rawSlice, ascii and crc32 built-in functions

[Gusarich]

Issue

Closes #444.

• slice() isn't actually an equivalent of any string literals, but just a more efficient way to define slice constants from BOC, similarly to cell()
• rawSlice("abcd") is an equivalent of "abcd"s in FunC
• ascii("hello world") is an equivalent of "hello world"u in FunC
• crc32("hello world") is an equivalent of "hello world"c in FunC

Checklist

• I have updated CHANGELOG.md
• I have documented my contribution in Tact Docs: https://github.com/tact-lang/tact-docs/pull/PR-NUMBER
• I have added tests to demonstrate the contribution is correctly implemented: this usually includes both positive and negative tests, showing the happy path(s) and featuring intentionally broken cases
• I have run all the tests locally and no test failure was reported
• I have run the linter, formatter and spellchecker
• I did not do unrelated and/or undiscussed refactorings

[anton-trunov]

1. What does slice and rawSlice correspond to in FunC string suffixes?
2. Let's add some negative tests, for instance, ascii("000000000000000000000000000000000") is supposed to fail due to overflow (33 zeros * 8 = 264 bits)`

[anton-trunov]

cspell

[Gusarich]

fixed

[anton-trunov]

Let's add a negative test with rawSlice(s) where s won't fit into a cell

[anton-trunov]

Great stuff!