GDB Refactor [21/N]: Move symbol.py to gdblib

[gsingh93]

A couple of changes to symbol.py other than the move:

• Private methods/variables now start with an underscore, making it easier to understand to understand methods/variables are being accessed from outside the module
• Added a few type annotations
• Fixed an issue where we were passing a byte string to pwndbg.symbol.address
• Removed the handling of integers or strings representing integers from pwndbg.symbol.address. I didn't see any usages of this in the codebase, and allowing so many arbitrary formats will lead to bugs
• Exceptions from gdb.lookup_symbol are no longer ignored, except for the one case of "No frame selected" errors. This is only occurring in the Go typeinfo tests, and I think the exception probably makes sense, but I want to dig into it a bit more and confirm the right fix is to use gdb.selected_frame() first.
• Removed the legacy way of looking up symbols with info address

[codecov-commenter]

Codecov Report

Merging #1259 (4143d55) into dev (ec8addd) will decrease coverage by 0.06%.
The diff coverage is 62.10%.

@@            Coverage Diff             @@
##              dev    #1259      +/-   ##
==========================================
- Coverage   54.52%   54.45%   -0.07%     
==========================================
  Files         182      182              
  Lines       20217    20214       -3     
  Branches     1865     1865              
==========================================
- Hits        11023    11008      -15     
- Misses       8761     8783      +22     
+ Partials      433      423      -10     

Impacted Files	Coverage Δ
pwndbg/commands/elf.py	26.31% <0.00%> (ø)
pwndbg/commands/probeleak.py	25.80% <0.00%> (ø)
pwndbg/gdblib/elf.py	40.08% <0.00%> (ø)
pwndbg/ghidra.py	16.27% <0.00%> (ø)
pwndbg/heap/ptmalloc.py	41.39% <34.48%> (ø)
pwndbg/commands/windbg.py	84.64% <50.00%> (ø)
pwndbg/gdblib/symbol.py	43.64% <56.00%> (ø)
pwndbg/commands/context.py	62.41% <66.66%> (ø)
pwndbg/arguments.py	59.09% <100.00%> (ø)
pwndbg/chain.py	81.03% <100.00%> (ø)
... and 17 more

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[gsingh93]

@CptGibbon @lebr0nli this PR is surfacing any exceptions that were previously caught when doing symbol lookup, and only ignoring a small set of them. On Ubuntu 18.04 and 20.04 (but not 22.04), I see the following exception in test_malloc_chunk_command_heuristic:

Do either of you know why that's happening? What's changed in libc since 20.04 that would result in this?

[CptGibbon]

Looks like the test binary needs to be linked against libpthread, I can submit a PR

[disconnect3d]

Should be:

skipped_exceptions = (
    # comment here
    "No frame selected",
    ...
)

but this can be changed in a next PR as well