feat(p/ufmt): Optimize `ufmt` package

[notJoon]

Description

This is an additional works for PR #4136. However, I couldn't push it directly, so I made this as a separate PR.

This PR includes various optimizations to improve the performance and memory usage of the ufmt package. In particular, it introduces lookahead[^1] approches to the format string parsing mechanism to enhance processing speed.

Key Improvements

1. Format Metadata Parsing Optimization

The existing parsing approach used multiple function calls and nested loops to parse format metadata. This has been replaced with a single-pass loop and lookahead technique, significantly improving processing speed.

Example parsing process (format string: %#+-0 15.8llx):

Existing method: Parsing each element individually
1. Parse '#' flag -> separate check
2. Parse '+', '-', '0', ' ' flags -> separate check for each
3. Parse '15' width -> call parseNumber function
4. Parse '.8' precision -> check for dot then call parseNumber function
5. Parse 'l', 'l' length modifiers -> iterate through all possible modifiers

Lookahead method: Parsing in a single pass
1. Detect '#' character -> set flagHashtag
2. Detect each flag character '+', '-', '0', ' ' -> set corresponding flag
3. Detect '15' number -> parse as width
4. Detect '.' dot -> check next character (lookahead) to parse precision
5. Detect 'l' -> lookahead next character to check if another 'l' exists
   -> If more 'l' exists, process as 'll' modifier at once

This approach is much more efficient, especially when parsing complex format specifiers.

2. Improved Buffer Management

Buffer management has been improved to optimize memory allocation:

• Enhanced Printf function to output directly without intermediate buffers

3. Function Inlining and Optimization

Several small functions have been partially inlined to reduce function call overhead

• Inlined the parseDigit function within parseNumber

Performance Measurement Method

Since we cannot directly verify performance line by line yet, we measured performance by outputting gas consumption from txtar tests that failed in the original PR. Although this isn't completely precise due to various influencing factors, it was considered a relatively reliable measurement method.

Tests were conducted using the TestRunMultiple_Integration test from gno.land/pkg/gnoclient/integration_test.go[^2].

go test -v ./gno.land/pkg/gnoclient -run TestRunMultiple_Integration

The gas consumption output from the original PR was:

=== RUN   TestRunMultiple_Integration
    integration_test.go:457: Gas used for first run: 23630623
(... failure afterwards ...)

We can see that only the first value is printed, and subsequent values are not output because the gas usage exceeds the requested value. When calculating the improvement ratio later, we will use 23630623 obtained here as an original usage.

The gas consumption after the modification was:

=== RUN   TestRunMultiple_Integration
    integration_test.go:457: Gas used for first run: 22194438
    integration_test.go:463: Gas used for second run: 22194595
--- PASS: TestRunMultiple_Integration (3.36s)
PASS
ok      github.com/gnolang/gno/gno.land/pkg/gnoclient   3.992s

Comparing only the numbers, we confirmed that the gas consumption improved as follows:

Reduction = 23,630,623 - 22,194,438 = 1,436,185
Improvement ratio = (Reduction / Original usage) × 100%
                  = (1,436,185 / 23,630,623) × 100%
                  ≈ 6.08%

[^1]: A method of making parsing decisions by examining tokens that appear after the current input token in advance. [^2]: https://github.com/gnolang/gno/blob/bb6a8842a921609ebd5e2fa4204de4d68ff5fe4d/gno.land/pkg/gnoclient/integration_test.go#L364

[Gno2D2]

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[thehowl]

Does this depend on #4136?

[notJoon]

Does this depend on #4136?

Yes, but not a prerequisite. it's an sort of alternative takes